FOOTNOTE:

[1] The evidence is given at length in R.H. Charles' _Ethiopic Text

of Enoch_, pp. xxvii-xxxiii.

ENOMOTO, BUYO, VISCOUNT (1839-1909), Japanese vice-admiral, was born in

Tokyo. He was the first officer sent by the Tokugawa government to study

naval science in Europe, and after going through a course of instruction

in Holland he returned in command of the frigate "Kaiyo Maru," built at

Amsterdam to order of the Yedo administration. The salient episode of

his career was an attempt to establish a republic at Hakodate. Finding

himself in command of a squadron which represented practically the whole

of Japan's naval forces, he refused to acquiesce in the deposition of

the Shogun, his liege lord, and, steaming off to Yezo (1867), proclaimed

a republic and fortified Hakodate. But he was soon compelled to

surrender. The newly organized government of the empire, however,

instead of inflicting the death penalty on him and his principal

followers, as would have been the inevitable sequel of such a drama in

previous times, punished them with imprisonment only, and four years

after the Hakodate episode, Enomoto received an important post in

Hokkaido, the very scene of his wild attempt. Subsequently (1874), as

his country's representative in St Petersburg, he concluded the treaty

by which Japan exchanged the southern half of Saghalien for the Kuriles.

He received the title of viscount in 1885, and afterwards held the

portfolios of communications, education and foreign affairs. He died at

Tokyo in 1909.

ENOS (anc. _Aenos_), a town of European Turkey, in the vilayet of

Adrianople; on the southern shore of the river Maritza, where its

estuary broadens to meet the Aegean Sea in the Gulf of Enos. Pop. (1905)

about 8000. Enos occupies a ridge of rock surrounded by broad marshes.

It is the seat of a Greek bishop, and the population is mainly Greek. It

long possessed a valuable export trade, owing to its position at the

mouth of the Maritza, the great natural waterway from Adrianople to the

sea. But its commerce has declined, owing to the unhealthiness of its

climate, to the accumulation of sandbanks in its harbour, which now only

admits small coasters and fishing-vessels, and to the rivalry of

Dedeagatch, a neighbouring seaport connected with Adrianople by rail.

ENRIQUEZ GOMEZ, ANTONIO (c. 1601-c. 1661), Spanish dramatist, poet and

novelist of Portuguese-Jewish origin, was known in the early part of his

career as Enrique Enriquez de Paz. Born at Segovia, he entered the army,

obtained a captaincy, was suspected of heresy, fled to France about

1636, assumed the name of Antonio Enriquez Gomez, and became majordomo

to Louis XIII., to whom he dedicated _Luis dado de Dios a Anna_ (Paris,

1645). Some twelve years later he removed to Amsterdam, avowed his

conversion to Judaism, and was burned in effigy at Seville on the 14th

of April 1660. He is supposed to have returned to France, and to have

died there in the following year. Three of his plays, _El Gran Cardenal

de Espana_, _don Gil de Albornoz_, and the two parts of _Fernan Mendez

Pinto_ were received with great applause at Madrid about 1629; in 1635

he contributed a sonnet to Montalban's collection of posthumous

panegyrics on Lope de Vega, to whose dramatic school Enriquez Gomez

belonged. The _Academias morales de las Musas_, consisting of four plays

(including _A lo que obliga el honor_, which recalls Calderon's _Medico

de su honra_), was published at Bordeaux in 1642; _La Torre de

Babilonia_, containing the two parts of _Fernan Mendez Pinto_, appeared

at Rouen in 1647; and in the preface to his poem, _El Samson Nazareno_

(Rouen, 1656), Enriquez Gomez gives the titles of sixteen other plays

issued, as he alleges, at Seville. There is no foundation for the theory

that he wrote the plays ascribed to Fernando de Zarate. His dramatic

works, though effective on the stage, are disfigured by extravagant

incidents and preciosity of diction. The latter defect is likewise

observable in the mingled prose and verse of _La Culpa del primer

peregrino_ (Rouen, 1644) and the dialogues entitled _Politica Angelica_

(Rouen, 1647). Enriquez Gomez is best represented by _El Siglo

Pitagorico y Vida de don Gregorio Guadana_ (Rouen, 1644), a striking

picaresque novel in prose and verse which is still reprinted.

ENSCHEDE, a town in the province of Overysel, Holland, near the

Prussian frontier, and a junction station 5 m. by rail S.E. of Hengelo.

Pop. (1900) 23,141. It is important as the centre of the flourishing

cotton-spinning and weaving industries of the Twente district; while by

the railway via Gronau and Koesfeld to Dortmund it is in direct

communication with the Westphalian coalfields. Enschede possesses

several churches, an industrial trade school, and a large park intended

for the benefit of the working classes. About two-thirds of the town was

burnt down in 1862.

ENSENADA, CENON DE SOMODEVILLA, MARQUES DE LA (1702-1781), Spanish

statesman, was born at Alesanco near Logrono on the 2nd of June 1702.

When he had risen to high office it was said that his pedigree was

distinguished, but nothing is known of his parents--Francisco de

Somodevilla and his wife Francisca de Bengoechea,--nor is anything known

of his own life before he entered the civil administration of the

Spanish navy as a clerk in 1720. He served in administrative capacities

at the relief of Ceuta in that year and in the reoccupation of Oran in

1731. His ability was recognized by Don Jose Patinos, the chief minister

of King Philip V. Somodevilla was much employed during the various

expeditions undertaken by the Spanish government to put the king's sons

by his second marriage with Elizabeth Farnese, Charles and Philip, on

the thrones of Naples and Parma. In 1736 Charles, afterwards King

Charles III. of Spain, conferred on him the Neapolitan title of Marques

de la Ensenada. The name can be resolved into the three Spanish words

"en se nada," meaning "in himself nothing." The courtly flattery of the

time, and the envy of the nobles who disliked the rise of men of

Ensenada's class, seized upon this poor play on words; an _Ensenada_ is,

however, a roadstead or small bay. In 1742 he became secretary of state

and war to Philip, duke of Parma. In the following year (11th of April

1743), on the death of Patinos's successor Campillo, he was chosen by

Philip V. as minister of finance, war, the navy and the Indies (i.e. the

Colonies). Ensenada met the nomination with a becoming _nolo

episcopari_, professing that he was incapable of filling the four posts

at once. His reluctance was overborne by the king, and he became in fact

prime minister at the age of forty-one. During the remainder of the

king's reign, which lasted till the 11th of July 1746, and under his

successor Ferdinand VI. until 1754, Ensenada was the effective prime

minister. His administration is notable in Spanish history for the

vigour of his policy of internal reform. The reports on the finances and

general condition of the country, which he drew up for the new king on

his accession, and again after peace was made with England at

Aix-la-Chapelle on the 18th of October 1748, are very able and

clear-sighted. Under his direction the despotism of the Bourbon kings

became paternal. Public works were undertaken, shipping was encouraged,

trade was fostered, numbers of young Spaniards were sent abroad for

education. Many of them abused their opportunity, but on the whole the

prosperity of the country revived, and the way was cleared for the more

sweeping innovations of the following reign. Ensenada was a strong

partizan of a French alliance and of a policy hostile to England. Sir B.

Keene, the English minister, supported the Spanish court party opposed

to him, and succeeded in preventing him from adding the foreign office

to others which he held. Ensenada would probably have fallen sooner but

for the support he received from the Portuguese queen, Barbara. In 1754

he offended her by opposing an exchange of Spanish and Portuguese

colonial possessions in America which she favoured. On the 20th of July

of that year he was arrested by the king's order, and sent into mild

confinement at Granada, which he was afterwards allowed to exchange for

Puerto de Santa Maria. On the accession of Charles III. in 1759, he was

released from arrest and allowed to return to Madrid. The new king named

him as member of a commission appointed to reform the system of

taxation. Ensenada could not renounce the hope of again becoming

minister, and entered into intrigues which offended the king. On the

18th of April 1766 he was again exiled from court, and ordered to go to

Medina del Campo. He had no further share in public life, and died on

the 2nd of December 1781. Ensenada acquired wealth in office, but he was

never accused of corruption. Though, like most of his countrymen, he

suffered from the mania for grandeur, and was too fond of imposing

schemes out of all proportion with the resources of the state, he was

undoubtedly an able and patriotic man, whose administration was

beneficial to Spain.

For his administration see W. Coxe, _Memoirs of the Kings of Spain of

the House of Bourbon_ (London, 1815), but the only complete account of

Ensenada is by Don Antonio Rodriguez Villa, _Don Cenon de Somodevilla,

Marques de la Ensenada_ (Madrid, 1878). (D. H.)

ENSIGN (through the Fr. _enseigne_ from the Latin plural _insignia_), a

distinguishing token, emblem or badge such as symbols of office, or in

heraldry, the ornament or sign, such as the crown, coronet or mitre

borne above the charge or arms. The word is more particularly used of a

military or naval standard or banner. In the British navy, ensign has a

specific meaning, and is the name of a flag having a red, white or blue

ground, with the Union Jack in the upper corner next the staff. The

white ensign (which is sometimes further distinguished by having the St

George's Cross quartered upon it) is only used in the royal navy and the

royal yacht squadron, while the blue and red ensigns are the badges of

the naval reserve, some privileged companies, and the merchant service

respectively (see FLAG). Until 1871 the lowest grade of commissioned

officers in infantry regiments of the British army had the title of

ensign (now replaced by that of second lieutenant). It is the duty of

the officers of this rank to carry the colours of the regiment (see

COLOURS, MILITARY). In the 16th century ensign was corrupted into

"ancient," and was used in the two senses of a banner and the bearer of

the banner. In the United States navy, the title ensign superseded in

1862 that of _passed midshipman_. It designates an officer ranking with

second lieutenant in the army.

ENSILAGE, the process of preserving green food for cattle in an undried

condition in a silo (from Gr. [Greek: siros], Lat. _sirus_, a pit for

holding grain), i.e. a pit, an erection above ground, or stack, from

which air has been as far as possible excluded. The fodder which is the

result of the process is called silage. In various parts of Germany a

method of preserving green fodder precisely similar to that used in the

case of _Sauerkraut_ has prevailed for upwards of a century. Special

attention was first directed to the practice of ensilage by a French

agriculturist, Auguste Goffart of the district of Sologne, near Orleans,

who in 1877 published a work (_Manuel de la culture et de l'ensilage des

mais et autres fourrages verts_) detailing the experiences of many years

in preserving green crops in silos. An English translation of Goffart's

book by J.B. Brown was published in New York in 1879, and, as various

experiments had been previously made in the United States in the way of

preserving green crops in pits, Goffart's experience attracted

considerable attention. The conditions of American dairy farming proved

eminently suitable for the ensiling of green maize fodder; and the

success of the method was soon indisputably demonstrated among the New

England farmers. The favourable results obtained in America led to much

discussion and to the introduction of the system in the United Kingdom,

where, with different conditions, success has been more qualified.

It has been abundantly proved that ensilage forms a wholesome and

nutritious food for cattle. It can be substituted for root crops with

advantage, because it is succulent and digestible; milk resulting from

it is good in quality and taste; it can be secured largely irrespective

of weather; it carries over grass from the period of great abundance and

waste to times when none would otherwise be available; and a larger

number of cattle can be supported on a given area by the use of ensilage

than is possible by the use of green crops.

Early silos were made of stone or concrete either above or below

ground, but it is recognized that air may be sufficiently excluded in a

tightly pressed stack, though in this case a few inches of the fodder

round the sides is generally useless owing to mildew. In America round

erections made of wood and 35 or 40 ft. in depth are most commonly used.

The crops suitable for ensilage are the ordinary grasses, clovers,

lucerne, vetches, oats, rye and maize, the latter being the most

important silage crop in America; various weeds may also be stored in

silos with good results, notably spurrey (_Spergula arvensis_), a most

troublesome plant in poor light soils. As a rule the crop should be mown

when in full flower, and deposited in the silo on the day of its

cutting. Maize is cut a few days before it is ripe and is shredded

before being elevated into the silo. Fair, dry weather is not essential;

but it is found that when moisture, natural and extraneous, exceeds 75%

of the whole, good results are not obtained. The material is spread in

uniform layers over the floor of the silo, and closely packed and

trodden down. If possible, not more than a foot or two should be added

daily, so as to allow the mass to settle down closely, and to heat

uniformly throughout. When the silo is filled or the stack built, a

layer of straw or some other dry porous substance may be spread over the

surface. In the silo the pressure of the material, when chaffed,

excludes air from all but the top layer; in the case of the stack extra

pressure is applied by means of planks or other weighty objects in order

to prevent excessive heating.

The closeness with which the fodder is packed determines the nature of

the resulting silage by regulating the chemical changes which occur in

the stack. When closely packed, the supply of oxygen is limited; and the

attendant acid fermentation brings about the decomposition of the

carbohydrates present into acetic, butyric and lactic acids. This

product is named "sour silage." If, on the other hand, the fodder be

unchaffed and loosely packed, or the silo be built gradually, oxidation

proceeds more rapidly and the temperature rises; if the mass be

compressed when the temperature is 140 deg.-160 deg. F., the action

ceases and "sweet silage" results. The nitrogenous ingredients of the

fodder also suffer change: in making sour silage as much as one-third of

the albuminoids may be converted into amino and ammonium compounds;

while in making "sweet silage" a less proportion is changed, but they

become less digestible. In extreme cases, sour silage acquires a most

disagreeable odour. On the other hand it keeps better than sweet silage

when removed from the silo.

ENSTATITE, a rock-forming mineral belonging to the group of orthorhombic

pyroxenes. It is a magnesium metasilicate, MgSiO3, often with a little

iron replacing the magnesium: as the iron increases in amount there is a

transition to bronzite (q.v.), and with still more iron to hypersthene

(q.v.). Bronzite and hypersthene were known long before enstatite, which

was first described by G.A. Kenngott in 1855, and named from [Greek:

enstates], "an opponent," because the mineral is almost infusible before

the blowpipe: the material he described consisted of imperfect prismatic

crystals, previously thought to be scapolite, from the serpentine of

Mount Zdjar near Schonberg in Moravia. Crystals suitable for goniometric

measurement were later found in the meteorite which fell at Breitenbach

in the Erzgebirge, Bohemia. Large crystals, a foot in length and mostly

altered to steatite, were found in 1874 in the apatite veins traversing

mica-schist and hornblende-schist at the apatite mine of Kjorrestad,

near Brevig in southern Norway. Isolated crystals are of rare

occurrence, the mineral being usually found as an essential constituent

of igneous rocks; either as irregular masses in plutonic rocks (norite,

peridotite, pyroxenite, &c.) and the serpentines which have resulted by

their alteration, or as small idiormorphic crystals in volcanic rocks

(trachyte, andesite). It is also a common constituent of meteoric

stones, forming with olivine the bulk of the material: here it often

forms small spherical masses, or chondrules, with an internal radiated

structure.

Enstatite and the other orthorhombic pyroxenes are distinguished from

those of the monoclinic series by their optical characters, viz.

straight extinction, much weaker double refraction and stronger

pleochroism: they have prismatic cleavages (with an angle of 88 deg.

16') as well as planes of parting parallel to the planes of symmetry in

the prism-zone. Enstatite is white, greenish or brown in colour; its

hardness is 5-1/2, and sp. gr. 3.2-3.3. (L. J. S.)

ENTABLATURE (Lat. _in_, and _tabula_, a tablet), the architectural term

for the superstructure carried by the columns in the classic orders

(q.v.). It usually consists of three members, the architrave (the

supporting member carried from column to column, pier or wall); the

frieze (the decorative member); and the cornice (the projecting and

protective member). Sometimes the frieze is omitted, as in the

entablature of the portico of the caryatides of the Erechtheum. There is

every reason to believe that the frieze did not exist in the archaic

temple of Diana at Ephesus; and it is not found in the Lycian tombs,

which are reproductions in the rock of timber structures based on early

Ionian work.

ENTADA, in botany, a woody climber belonging to the family _Leguminosae_

and common throughout the tropics. The best-known species is _Entada

scandens_, the sword-bean, so called from its large woody pod, 2 to 4

ft. in length and 3 to 4 in. broad, which contains large flat hard

polished chestnut-coloured seeds or "beans." The seeds are often made

into snuff-boxes or match-boxes, and a preparation from the kernel is

used as a drug by the natives in India. The seeds will float for a long

time in water, and are often thrown up on the north-western coasts of

Europe, having been carried by the Gulf-stream from the West Indies;

they retain their vitality, and under favourable conditions will

germinate. Linnaeus records the germination of a seed on the coast of

Norway.

ENTAIL (from Fr. _tailler_, to cut; the old derivation from _tales

haeredes_ is now abandoned), in law, a limited form of succession

(q.v.). In architecture, the term "entail" denotes an ornamental device

sunk in the ground of stone or brass, and subsequently filled in with

marble, mosaic or enamel.

ENTASIS (from Gr. [Greek: enteinein], to stretch a line or bend a bow),

in architecture, the increment given to the column (q.v.), to correct

the optical illusion which produces an apparent hollowness in an

extended straight line. It was referred to by Vitruvius (iii. 3), and

was first noticed in the columns of the Doric orders in Greek temples by

Allason in 1814, and afterwards measured and verified by Penrose. It

varies in different temples, and is not found in some: it is most

pronounced in the temple of Jupiter Olympius, most delicate in the

Erechtheum. The entasis is almost invariably introduced in the spires of

English churches.

ENTERITIS (Gr. [Greek: enteron], intestine), a general medical term for

inflammation of the bowels. According to the anatomical part specially

attacked, it is subdivided into duodenitis, jejunitis, ileitis,

typhlitis, appendicitis, colitis, proctitis. The chief symptom is

diarrhoea. The term "enteric fever" has recently come into use instead

of "typhoid" for the latter disease; but see TYPHOID FEVER.

ENTHUSIASM, a word originally meaning inspiration by a divine afflatus

or by the presence of a god. The Gr. [Greek: enthousiasmos], from which

the word is adapted, is formed from the verb [Greek: enthousiazein], to

be [Greek: entheos], possessed by a god [Greek: theos]. Applied by the

Greeks to manifestations of divine "possession," by Apollo, as in the

case of the Pythia, or by Dionysus, as in the case of the Bacchantes and

Maenads, it was also used in a transferred or figurative sense; thus

Socrates speaks of the inspiration of poets as a form of enthusiasm

(Plato, _Apol. Soc._ 22 C). Its uses, in a religious sense, are confined

to an exaggerated or wrongful belief in religious inspiration, or to

intense religious fervour or emotion. Thus a Syrian sect of the 4th

century was known as "the Enthusiasts"; they believed that by perpetual

prayer, ascetic practices and contemplation, man could become inspired

by the Holy Spirit, in spite of the ruling evil spirit, which the fall

had given to him. From their belief in the efficacy of prayer [Greek:

euche], they were also known as Euchites. In ordinary usage,

"enthusiasm" has lost its peculiar religious significance, and means a

whole-hearted devotion to an ideal, cause, study or pursuit; sometimes,

in a depreciatory sense, it implies a devotion which is partisan and is

blind to difficulties and objections. (See further INSPIRATION, for a

comparison of the religious meanings of "enthusiasm," "ecstasy" and

"fanaticism.")

ENTHYMEME (Gr. [Greek: en, thymos]), in formal logic, the technical

name of a syllogistic argument which is incompletely stated. Any one of

the premises may be omitted, but in general it is that one which is most

obvious or most naturally present to the mind. In point of fact the full

formal statement of a syllogism is rare, especially in rhetorical

language, when the deliberate omission of one of the premises has a

dramatic effect. Thus the suppression of the conclusion may have the

effect of emphasizing the idea which necessarily follows from the

premises. Far commoner is the omission of one of the premises which is

either too clear to need statement or of a character which makes its

omission desirable. A famous instance quoted in the _Port Royal Logic_,

pt. iii. ch. xiv., is Medea's remark to Jason in Ovid's _Medea_,

"Servare potui, perdere an possim rogas?" where the major premise "Qui

servare, perdere possunt" is understood. This use of the word enthymeme

differs from Aristotle's original application of it to a syllogism based

on probabilities or signs ([Greek: ex eikoton e semeion]), i.e. on

propositions which are generally valid ([Greek: eikota]) or on

particular facts which may be held to justify a general principle or

another particular fact (_Anal. prior._ [beta] xxvii. 70 a 10).

See beside text-books on logic, Sir W. Hamilton's _Discussions_

(1547); Mansel's ed. of Aldrich, Appendix F; H.W.B. Joseph, _Introd.

to Logic_, chap. xvi.

ENTOMOLOGY (Gr. [Greek: entoma,] insects, and [Greek: logos], a

discourse), the science that treats of insects, i.e. of the animals

included in the class Hexapoda of the great phylum (or sub-phylum)

Arthropoda. The term, however, is somewhat elastic in its current use,

and students of centipedes and spiders are often reckoned among the

entomologists. As the number of species of insects is believed to exceed

that of all other animals taken together, it is no wonder that their

study should form a special division of zoology with a distinctive name.

Beetles (Scarabaei) are the subjects of some of the oldest sculptured

works of the Egyptians, and references to locusts, bees and ants are

familiar to all readers of the Hebrew scriptures. The interest of

insects to the eastern races was, however, economic, religious or moral.

The science of insects began with Aristotle, who included in a class

"Entoma" the true insects, the arachnids and the myriapods, the

Crustacea forming another class ("Malacostraca") of the "Anaema" or

"bloodless animals." For nearly 2000 years the few writers who dealt

with zoological subjects followed Aristotle's leading.

In the history of the science, various lines of progress have to be

traced. While some observers have studied in detail the structure and

life-history of a few selected types (insect anatomy and development),

others have made a more superficial examination of large series of

insects to classify them and determine their relationships (systematic

entomology), while others again have investigated the habits and

life-relations of insects (insect bionomics). During recent years the

study of fossil insects (palaeoentomology) has attracted much attention.

The foundations of modern entomology were laid by a series of wonderful

memoirs on anatomy and development published in the 17th and 18th

centuries. Of these the most famous are M. Malpighi's treatise on the

silkworm (1669) and J. Swammerdam's _Biblia naturae_, issued in 1737,

fifty years after its author's death, and containing observations on the

structure and life-history of a series of insect types. Aristotle and

Harvey (_De generatione animalium_, 1651) had considered the insect larva

as a prematurely hatched embryo and the pupa as a second egg. Swammerdam,

however, showed the presence under the larval cuticle of the pupal

structures. His only unfortunate contribution to entomology--indeed to

zoology generally--was his theory of pre-formation, which taught the

presence within the egg of a perfectly formed but miniature adult. A year

before Malpighi's great work appeared, another Italian naturalist, F.

Redi, had disproved by experiment the spontaneous generation of maggots

from putrid flesh, and had shown that they can only develop from the eggs

of flies.

Meanwhile the English naturalist, John Ray, was studying the

classification of animals; he published, in 1705, his _Methodus

insectorum_, in which the nature of the metamorphosis received due

weight. Ray's "Insects" comprised the Arachnids, Crustacea, Myriapoda

and Annelida, in addition to the Hexapods. Ray was the first to

formulate that definite conception of the species which was adopted by

Linnaeus and emphasized by his binominal nomenclature. In 1735 appeared

the first edition of the _Systema naturae_ of Linnaeus, in which the

"Insecta" form a group equivalent to the Arthropoda of modern

zoologists, and are divided into seven orders, whose names--Coleoptera,

Diptera, Lepidoptera, &c., founded on the nature of the wings--have

become firmly established. The fascinating subjects of insect bionomics

and life-history were dealt with in the classical memoirs (1734-1742) of

the Frenchman R.A.F. de Reaumur, and (1752-1778) of the Swede C. de

Geer. The freshness, the air of leisure, the enthusiasm of discovery

that mark the work of these old writers have lessons for the modern

professional zoologist, who at times feels burdened with the accumulated

knowledge of a century and a half. From the end of the 18th century

until the present day, it is only possible to enumerate the outstanding

features in the progress of entomology. In the realm of classification,

the work of Linnaeus was continued in Denmark by J.C. Fabricius

(_Systema entomologica_, 1775), and extended in France by G.P.B. Lamarck

(_Animaux sans vertebres_, 1801) and G. Cuvier (_Lecons d'anatomie

comparee_, 1800-1805), and in England by W.E. Leach (_Trans. Linn. Soc._

xi., 1815). These three authors definitely separated the Arachnida,

Crustacea and Myriapoda as classes distinct from the Insecta (see

HEXAPODA). The work of J.O. Westwood (_Modern Classification of

Insects_, 1839-1840) connects these older writers with their successors

of to-day.

In the anatomical field the work of Malpighi and Swammerdam was at first

continued most energetically by French students. P. Lyonnet had

published in 1760 his elaborate monograph on the goat-moth caterpillar,

and H.E. Strauss-Durckheim in 1828 issued his great treatise on the

cockchafer. But the name of J.C.L. de Savigny, who (_Mem. sur les

animaux sans vertebres_, 1816) established the homology of the jaws of

all insects whether biting or sucking, deserves especial honour. Many

anatomical and developmental details were carefully worked out by L.

Dufour (in a long series of memoirs from 1811 to 1860) in France, by G.

Newport ("Insecta" in _Encyc. Anat. and Physiol._, 1839) in England, and

by H. Burmeister (_Handbuch der Entomologie_, 1832) in Germany. Through

the 19th century, as knowledge increased, the work of investigation

became necessarily more and more specialized. Anatomists like F. Leydig,

F. Muller, B.T. Lowne and V. Graber turned their attention to the

detailed investigation of some one species or to special points in the

structure of some particular organs, using for the elucidation of their

subject the ever-improving microscopical methods of research.

Societies for the discussion and publication of papers on entomology

were naturally established as the number of students increased. The

Societe Entomologique de France was founded in 1832, the Entomological

Society of London in 1834. Few branches of zoology have been more

valuable as a meeting-ground for professional and amateur naturalists

than entomology, and not seldom has the amateur--as in the case of

Westwood--developed into a professor. During the pre-Linnaean period,

the beauty of insects--especially the Lepidoptera--had attracted a

number of collectors; and these "Aurelians"--regarded as harmless

lunatics by most of their friends--were the forerunners of the

systematic students of later times. While the insect fauna of European

countries was investigated by local naturalists, the spread of

geographical exploration brought ever-increasing stores of exotic

material to the great museums, and specialization--either in the fauna

of a small district or in the world-wide study of an order or a group of

families--became constantly more marked in systematic work. As examples

may be instanced the studies of A.H. Haliday and H. Loew on the European

Diptera, of John Curtis on British insects, of H.T. Stainton and O.

Staudinger on the European Lepidoptera, of R. M'Lachlan on the European

and of H.A. Hagen on the North American Neuroptera, of D. Sharp on the

_Dyticidae_ and other families of Coleoptera of the whole world.

The embryology of insects is entirely a study of the last century. C.

Bonnet indeed observed in 1745 the virgin-reproduction of Aphids, but it

was not until 1842 that R.A. von Kolliker described the formation of the

blastoderm in the egg of the midge _Chironomus_. Later A. Weismann

(1863-1864) traced details of the growth of embryo and of pupa among the

Diptera, and A. Kovalevsky in 1871 first described the formation of the

germinal layers in insects. Most of the recent work on the embryology of

insects has been done in Germany or the United States, and among

numerous students V. Graber, K. Heider, W.M. Wheeler and R. Heymons may

be especially mentioned.

The work of de Reaumur and de Geer on the bionomics and life-history of

insects has been continued by numerous observers, among whom may be

especially mentioned in France J.H. Fabre and C. Janet, in England W.

Kirby and W. Spence, J. Lubbock (Lord Avebury) and L.C. Miall, and in

the United States C.V. Riley. The last-named may be considered the

founder of the strong company of entomological workers now labouring in

America. Though Riley was especially interested in the bearings of

insect life on agriculture and industry--economic entomology (q.v.)--he

and his followers have laid the science generally under a deep

obligation by their researches.

After the publication of C. Darwin's _Origin of Species_ (1859) a fresh

impetus was given to entomology as to all branches of zoology, and it

became generally recognized that insects form a group convenient and

hopeful for the elucidation of certain problems of animal evolution. The

writings of Darwin himself and of A.R. Wallace (both at one time active

entomological collectors) contain much evidence drawn from insects in

favour of descent with modification. The phylogeny of insects has since

been discussed by F. Brauer, A.S. Packard and many others; mimicry and

allied problems by H.W. Bates, F. Muller, E.B. Poulton and M.C. Piepers;

the bearing of insect habits on theories of selection and

use-inheritance by A. Weismann, G.W. and E. Peckham, G.H.T. Eimer and

Herbert Spencer; variation by W. Bateson and M. Standfuss.

BIBLIOGRAPHY.--References to the works of the above authors, and to

many others, will be found under HEXAPODA and the special articles on

various insect orders. Valuable summaries of the labours of Malpighi,

Swammerdam and other early entomologists are given in L.C. Miall and

A. Denny's _Cockroach_ (London, 1886), and L. Henneguy's _Les

Insectes_ (Paris, 1904). (G. H. C.)

ENTOMOSTRACA. This zoological term, as now restricted, includes the

Branchiopoda, Ostracoda and Copepoda. The Ostracoda have the body

enclosed in a bivalve shell-covering, and normally unsegmented. The

Branchiopoda have a very variable number of body-segments, with or

without a shield, simple or bivalved, and some of the postoral

appendages normally branchial. The Copepoda have normally a segmented

body, not enclosed in a bivalved shell-covering, the segments not

exceeding eleven, the limbs not branchial.

Under the heading CRUSTACEA the Entomostraca have already been

distinguished not only from the Thyrostraca or Cirripedes, but also from

the Malacostraca, and an intermediate group of which the true position

is still disputed. The choice is open to maintain the last as an

independent subclass, and to follow Claus in calling it the Leptostraca,

or to introduce it among the Malacostraca as the Nebaliacea, or with

Packard and Sars to make it an entomostracan subdivision under the title

Phyllocarida. At present it comprises the single family _Nebaliidae_.

The bivalved carapace has a jointed rostrum, and covers only the front

part of the body, to which it is only attached quite in front, the

valve-like sides being under control of an adductor muscle. The eyes are

stalked and movable. The first antennae have a lamellar appendage at the

end of the peduncle, a decidedly non-entomostracan feature. The second

antennae, mandibles and two pairs of maxillae may also be claimed as of

malacostracan type. To these succeed eight pairs of foliaceous branchial

appendages on the front division of the body, followed on the hind

division by four pairs of powerful bifurcate swimming feet and two

rudimentary pairs, the number, though not the nature, of these

appendages being malacostracan. On the other hand, the two limbless

segments that precede the caudal furca are decidedly non-malacostracan.

The family was long limited to the single genus _Nebalia_ (Leach), and

the single species _N. bipes_ (O. Fabricius). Recently Sars has added a

Norwegian species, _N. typhlops_, not blind but weak-eyed. There are

also now two more genera, _Paranebalia_ (Claus, 1880), in which the

branchial feet are much longer than in _Nebalia_, and _Nebaliopsis_

(Sars, 1887), in which they are much shorter. All the species are

marine.

BRANCHIOPODA.--In this order, exclusion of the Phyllocarida will leave

three suborders of very unequal extent, the Phyllopoda, Cladocera,

Branchiura. The constituents of the last have often been classed as

Copepoda, and among the Branchiopods must be regarded as aberrant, since

the "branchial tail" implied in the name has no feet, and the actual

feet are by no means obviously branchial.

_Phyllopoda._--This "leaf-footed" suborder has the appendages which

follow the second maxillae variable in number, but all foliaceous and

branchial. The development begins with a free nauplius stage. In the

outward appearance of the adults there is great want of uniformity, one

set having their limbs sheltered by no carapace, another having a broad

shield over most of them, and a third having a bivalved shell-cover

within which the whole body can be enclosed. In accord with these

differences the sections may be named Gymnophylla, Notophylla,

Conchophylla. The equivalent terms applied by Sars are Anostraca,

Notostraca, Conchostraca, involving a termination already appropriated

to higher divisions of the Crustacean class, for which it ought to be

reserved.

1. Gymnophylla.--These singular crustaceans have long soft flexible

bodies, the eyes stalked and movable, the first antennae small and

filiform, the second lamellar in the female, in the male prehensile;

this last character gives rise to some very fanciful developments.

There are three families, two of which form companies rather severely

limited. Thus the _Polyartemiidae_, which compensate themselves for

their stumpy little tails by having nineteen instead of the normal

eleven pairs of branchial feet, consist exclusively of _Polyartemia

forcipata_ (Fischer, 1851). This species from the high north of Europe

and Asia carries green eggs, and above them a bright pattern in

ultramarine (Sars, 1896, 1897). The _Thamnocephalidae_ have likewise

but a single species, _Thamnocephalus platyurus_ (Packard, 1877),

which justifies its title "bushy-head of the broad tail" by a

singularity at each end. Forward from the head extends a long ramified

appendage described as the "frontal shrub," backward from the fourth

abdominal segment of the male spreads a fin-like expansion which is

unique. In the ravines of Kansas, pools supplied by torrential rains

give birth to these and many other phyllopods, and in turn "millions

of them perish by the drying up of the pools in July" (Packard). The

remaining family, the _Branchipodidae_, includes eight genera. In the

long familiar _Branchipus_, _Chirocephalus_ and _Streptocephalus_ the

males have frontal appendages, but these are wanting in the

"brine-shrimp" _Artemia_, and the same want helps to distinguish

_Branchinecta_ (Verrill, 1869) from the old genus _Branchipus_. Of

_Branchiopsyllus_ (Sars, 1897) the male is not yet known, but in his

genera of the same date, the Siberian _Artemiopsis_ and the South

African _Branchipodopsis_ (1898), there is no such appendage. Of the

last genus the type species _B. hodgsoni_ belongs to Cape Colony, but

the specimens described were born and bred and observed in Norway. For

the study of fresh-water Entomostraca large possibilities are now

opened to the naturalist. A parcel of dried mud, coming for example

from Palestine or Queensland, and after an indefinite interval of time

put into water in England or elsewhere, may yield him living forms,

both new and old, in the most agreeable variety. Some caution should

be used against confounding accidentally introduced indigenous species

with those reared from the imported eggs. Those, too, who send or

bring the foreign soil should exercise a little thought in the choice

of it, since dry earth that has never had any Entomostraca near it at

home will not become fertile in them by the mere fact of exportation.

2. Notophylla.--In this division the body is partly covered by a broad

shield, united in front with the head; the eyes are sessile, the first

antennae are small, the second rudimentary or wanting; of the numerous

feet, sometimes sixty-three pairs, exceeding the number of segments to

which they are attached, the first pair are more or less unlike the

rest, and in the female the eleventh have the epipod and exopod

(flabellum and sub-apical lobe of Lankester) modified to form an

ovisac. Development begins with a nauplius stage. Males are very rare.

The single family _Apodidae_ contains only two genera, _Apus_ and its

very near neighbour _Lepidurus_. _Apus australiensis_ (Spencer and

Hall, 1896) may rank as the largest of the Entomostraca, reaching in

the male, from front of shield to end of telson, a length of 70 mm.,

in the female of 64 mm. In a few days, or at most a fortnight, after a

rainfall numberless specimens of these sizes were found swimming

about, "and as not a single one was to be found in the water-pools

prior to the rain, these must have been developed from the egg."

Similarly, in Northern India _Apus himalayanus_ was "collected from a

stagnant pool in a jungle four days after a shower of rain had

fallen," following a drought of four months (Packard).

3. Conchophylla.--Though concealed within the bivalved shell-cover,

the mouth-parts are nearly as in the Gymnophylla, but the flexing of

the caudal part is in contrast, and the biramous second antennae

correspond with what is only a larval character in the other

phyllopods. In the male the first one or two pairs of feet are

modified into grasping organs. The small ova are crowded beneath the

dorsal part of the valves. The development usually begins with a

nauplius stage (Sars, 1896, 1900). There are four families: (a) The

_Limnadiidae_, with feet from 18 to 32 pairs, comprise four (or five)

genera. Of these _Limnadella_ (Girard, 1855) has a single eye. It

remains rather obscure, though the type species originally "was

discovered in great abundance in a roadside puddle subject to

desiccation." _Limnadia_ (Brongniart, 1820) is supposed to consist of

species exclusively parthenogenetic. But when asked to believe that

males never occur among these amazons, one cannot but remember how

hard it is to prove a negative. (b) The _Lynceidae_, with not more

than twelve pairs of feet. This family is limited to the species,

widely distributed, of the single genus _Lynceus_, established by O.F.

Muller in 1776 and 1781, and first restricted by Leach in 1816 in the

_Encyclopaedia Britannica_ (art. "Annulosa," of that edition). Leach

there assigns to it the single species _L. brachyurus_ (Muller), and

as this is included in the genus _Limnetis_ (Loven, 1846), that genus

must be a synonym of _Lynceus_ as restricted. (c) _Leptestheriidae_.

_Estheria_ (Ruppell, 1837) was instituted for the species

_dahalacensis_, which Sars includes in his genus _Leptestheria_

(1898); but _Estheria_ was already appropriated, and of its synonyms

_Cyzicus_ (Audouin, 1837) is lost for vagueness, while _Isaura_ (Joly,

1842) is also appropriated, so that _Leptestheria_ becomes the name of

the typical genus, and determines the name of the family. (d)

_Cyclestheriidae_. This family consists of the single species

_Cyclestheria hislopi_ (Baird), reported from India, Ceylon, Celebes,

Australia, East Africa and Brazil. Sars (1887) having had the

opportunity of raising it from dried Australian mud, found that,

unlike other phyllopods, but like the Cladocera, the parent keeps its

brood within the shell until their full development.

_Cladocera._--In this suborder the head is more or less distinct, the

rest of the body being in general laterally compressed and covered by a

bivalved test. The title "branching horns" alludes to the second

antennae, which are two-branched except in the females of _Holopedium_,

with each branch setiferous, composed of only two to four joints. The

mandibles are without palp. The pairs of feet are four to six. The eye

is single, and in addition to the eye there is often an "eye-spot,"

_Monospilus_ being unique in having the eye-spot alone and no eye, while

_Leydigiopsis_ (Sars, 1901) has an eye with an eye-spot equal to it or

larger. The heart has a pair of venous ostia, often blending into one,

and an anterior arterial aorta. Respiration is conducted by the general

surface, by the branchial lamina (external branch) of the feet, and the

vesicular appendage (when present) at the base of this branch. The

"abdomen," behind the limbs, is usually very short, occasionally very

long. The "postabdomen," marked off by the two postabdominal setae,

usually has teeth or spines, and ends in two denticulate or ciliate

claws, or it may be rudimentary, as in _Polyphemus_. Many species have a

special glandular organ at the back of the head, which _Sida

crystallina_ uses for attaching itself to various objects. The Leydigian

or nuchal organ is supposed to be auditory and to contain an otolith.

The female lays two kinds of eggs--"summer-eggs," which develop without

fertilization, and "winter-eggs" or resting eggs, which require to be

fertilized. The latter in the _Daphniidae_ are enclosed in a modified

part of the mother's shell, called the ephippium from its resemblance to

a saddle in shape and position. In other families a less elaborate case

has been observed, for which Scourfield has proposed the term

protoephippium. In _Leydigia_ he has recently found a structure almost

as complex as that of the _Daphniidae_. In some families the resting

eggs escape into the water without special covering. Only the embryos of

_Leptodora_ are known to hatch out in the nauplius stage. _Penilia_

(Dana, 1849) is perhaps the only exclusively marine genus. The great

majority of the Cladocera belong to fresh water, but their adaptability

is large, since _Moina rectirostris_ (O.F. Muller) can equally enjoy a

pond at Blackheath, and near Odessa live in water twice as salt as that

of the ocean. In point of size a Cladoceran of 5 mm. is spoken of as

colossal.

Dr Jules Richard in his revision (1895) retains the sections proposed

by Sars in 1865, Calyptomera and Gymnomera. The former, with the feet

for the most part concealed by the carapace, is subdivided into two

tribes, the Ctenopoda, or "comb-feet," in which the six pairs of

similar feet, all branchial and nonprehensile, are furnished with

setae arranged like the teeth of a comb, and the Anomopoda, or

"variety-feet," in which the front feet differ from the rest by being

more or less prehensile, without branchial laminae.

The Ctenopoda comprise two families: (a) the _Holopediidae_, with a

solitary species, _Holopedium gibberum_ (Zaddach), queerly clothed in

a large gelatinous involucre, and found in mountain tarns all over

Europe, in large lakes of N. America, and also in shallow ponds and

waters at sea-level; (b) the _Sididae_, with no such involucre, but

with seven genera, and rather more than twice as many species. Of

_Diaphanosoma modiglianii_ Richard says that at different points of

Lake Toba in Sumatra millions of specimens were obtained, among which

he had not met with a single male.

The Anomopoda are arranged in four families, all but one very

extensive. (a) _Daphniidae_. Of the seven genera, the cosmopolitan

_Daphnia_ contains about 100 species and varieties, of which Thomas

Scott (1899) observes that "scarcely any of the several characters

that have at one time or another been selected as affording a means

for discriminating between the different forms can be relied on as

satisfactory." Though this may dishearten the systematist, Scourfield

(1900) reminds us that "It was in a water-flea that Metschnikoff first

saw the leucocytes (or phagocytes) trying to get rid of disease germs

by swallowing them, and was so led to his epoch-making discovery of

the part played by these minute amoeboid corpuscles in the animal

body." For _Scapholeberis mucronata_ (O.F. Muller), Scourfield has

shown how it is adapted for movement back downwards in the water along

the underside of the surface film, which to many small crustaceans is

a dangerously disabling trap. (b) _Bosminidae_. To _Bosmina_ (Baird,

1845) Richard added _Bosminopsis_ in 1895. (c) _Macrotrichidae._ In

this family _Macrothrix_ (Baird, 1843) is the earliest genus, among

the latest being _Grimaldina_ (Richard, 1892) and _Jheringula_ (Sars,

1900). Dried mud and vegetable debris from S. Paulo in Brazil supplied

Sars with representatives of all the three in his Norwegian aquaria,

in some of which the little _Macrothrix elegans_ "multiplied to such

an extraordinary extent as at last to fill up the water with immense

shoals of individuals." "The appearance of male specimens was always

contemporary with the first ephippial formation in the females." For

_Streblocerus pygmaeus_, grown under the same conditions, Sars

observes: "This is perhaps the smallest of the Cladocera known, and is

hardly more than visible to the naked eye," the adult female scarcely

exceeding 0.25 mm. Yet in the next family _Alonella nana_ (Baird)

disputes the palm and claims to be the smallest of all known

Arthropoda. (d) _Chydoridae._ This family, so commonly called

_Lynceidae_, contains a large number of genera, among which one may

usually search in vain, and rightly so, for the genus _Lynceus_. The

key to the riddle is to be found in the _Encyclopaedia Britannica_ for

1816. There, as above explained, Leach began the subdivision of

Muller's too comprehensive genus, the result being that _Lynceus_

belongs to the Phyllopoda, and _Chydorus_ (Leach, 1816) properly gives

its name to the present family, in which the doubly convoluted

intestine is so remarkable. Of its many genera, _Leydigia_,

_Leydigiopsis_, _Monospilus_ have been already mentioned. _Dadaya

macrops_ (Sars, 1901), from South America and Ceylon, has a very large

eye and an eye-spot fully as large, but it is a very small creature,

odd in its behaviour, moving by jumps at the very surface of the

water. "To the naked eye it looked like a little black atom darting

about in a most wonderful manner."

[Illustration: FIG. 1.--_Dolops ranarum_ (Stuhlmann).]

The Gymnomera, with a carapace too small to cover the feet, which are

all prehensile, are divided also into two tribes, the Onychopoda, in

which the four pairs of feet have a toothed maxillary process at the

base, and the Haplopoda, in which there are six pairs of feet, without

such a process. To the _Polyphemidae_, the well-known family of the

former tribe, Sars in 1897 added two remarkable genera, _Cercopagis_,

meaning "tail with a sling," and _Apagis_, "without a sling," for

seven species from the Sea of Azov. The Haplopoda likewise have but a

single family, the _Leptodoridae_, and this has but the single genus

_Leptodora_ (Lilljeborg, 1861). Dr Richard (1895, 1896) gives a

Cladoceran bibliography of 601 references.

_Branchiura._--This term was introduced by Thorell in 1864 for the

_Argulidae_, a family which had been transferred to the Branchiopoda by

Zenker in 1854, though sometimes before and since united with the

parasitic Copepoda. Though the animals have an oral siphon, they do not

carry ovisacs like the siphonostomous copepods, but glue their eggs in

rows to extraneous objects. Their lateral, compound, feebly movable eyes

agree with those of the Phyllopoda. The family are described by Claus as

"intermittent parasites," because when gorged they leave their hosts,

fishes or frogs, and swim about in freedom for a considerable period.

The long-known _Argulus_ (O.F. Muller) has the second maxillae

transformed into suckers, but in _Dolops_ (Audouin, 1837) (fig. 1), the

name of which supersedes the more familiar _Gyropeltis_ (Heller, 1857),

these effect attachment by ending in strong hooks (Bouvier, 1897). A

third genus, _Chonopeltis_ (Thiele, 1900), has suckers, but has lost its

first antennae, at least in the female.

OSTRACODA.--The body, seldom in any way segmented, is wholly encased in

a bivalved shell, the caudal part strongly inflexed, and almost always

ending in a furca. The limbs, including antennae and mouth organs, never

exceed seven definite pairs. The first antennae never have more than

eight joints. The young usually pass through several stages of

development after leaving the egg, and this commonly after, even long

after, the egg has left the maternal shell. Parthenogenesis is frequent.

The four tribes instituted by Sars in 1865 were reduced to two by G.W.

Muller in 1894, the Myodocopa, which almost always have a heart, and the

Podocopa, which have none.

_Myodocopa._--These have the furcal branches broad, lamellar, with at

least three pairs of strong spines or ungues. Almost always the shell

has a rostral sinus. Muller divides the tribe into three families,

_Cypridinidae, Halocypridae_, and the heartless _Polycopidae_, which

constituted the tribe Cladocopa of Sars. From the first of these Brady

and Norman distinguish the Asteropidae (fig. 3), remarkable for seven

pairs of long branchial leaves which fold over the hinder extremity of

the animal, and the _Sarsiellidae_, still somewhat obscure, besides

adding the _Rutidermatidae_, knowledge of which is based on skilful

maceration of minute and long-dried specimens. The _Halocypridae_ are

destitute of compound lateral eyes, and have the sexual orifice

unsymmetrically placed.

_Podocopa._--In these the furcal branches are linear or rudimentary,

the shell is without rostral sinus, and, besides distinguishing

characters of the second antennae, they have always a branchial plate

well developed on the first maxillae, which is inconstant in the other

tribe. There are five families: (a) _Cyprididae_ (? including

_Cypridopsidae_ of Brady and Norman). In some of the genera

parthenogenetic propagation is carried to such an extent that of the

familiar _Cypris_ it is said, "until quite lately males in this genus

were unknown; and up to the present time no male has been found in the

British Islands" (Brady and Norman, 1896). On the other hand, the

ejaculatory duct with its verticillate sac in the male of _Cypris_ and

other genera is a feature scarcely less remarkable. (b) _Bairdiidae_,

which have the valves smooth, with the hinge untoothed. (c)

_Cytheridae_ (? including _Paradoxostomatidae_ of Brady and Norman),

in which the valves are usually sculptured, with toothed hinge. Of

this family the members are almost exclusively marine, but

_Limnicythere_ is found in fresh water, and _Xestoleberis bromeliarum_

(Fritz Muller) lives in the water that collects among the leaves of

Bromelias, plants allied to the pine-apples. (d) _Darwinulidae_,

including the single species _Darwinula stevensoni_, Brady and

Robertson, described as "perhaps the most characteristic Entomostracan

of the East Anglian Fen District." (e) _Cytherellidae_, which, unlike

the Ostracoda in general, have the hinder part of the body segmented,

at least ten segments being distinguishable in the female. They have

the valves broad at both ends, and were placed by Sars in a separate

tribe, called Platycopa.

The range in time of the Ostracoda is so extended that, in G.W.

Muller's opinion, their separation into the families now living may have

already taken place in the Cambrian period. Their range in space,

including carriage by birds, may be coextensive with the distribution of

water, but it is not known what height of temperature or how much

chemical adulteration of the water they can sustain, how far they can

penetrate underground, nor what are the limits of their activity between

the floor and the surface of aquatic expanses, fresh or saline. In

individual size they have never been important, and of living forms the

largest is one of recent discovery, _Crossophorus africanus_, a

Cypridinid about three-fifths of an inch (15.5 mm.) long; but a length

of one or two millimetres is more common, and it may descend to the

seventy-fifth of an inch. By multitude they have been, and still are,

extremely important.

Though the exterior is more uniform than in most groups of Crustacea,

the bivalved shell or carapace may be strongly calcified and diversely

sculptured (fig. 2), or membranaceous and polished, hairy or smooth,

oval or round or bean-shaped, or of some less simple pattern; the

valves may fit neatly, or one overlap the other, their hinge may have

teeth or be edentulous, and their front part may be excavated for the

protrusion of the antennae or have no such "rostral sinus." By various

modifications of their valves and appendages the creatures have become

adapted for swimming, creeping, burrowing, or climbing, some of them

combining two or more of these activities, for which their structure

seems at the first glance little adapted. Considering the imprisonment

of the ostracod body within the valves, it is more surprising that the

_Asteropidae_ and _Cypridinidae_ should have a pair of compound and

sometimes large eyes, in addition to the median organ at the base of

the "frontal tentacle," than that other members of the group should be

limited to that median organ of sight, or have no eyes at all. The

median eye when present may have or not have a lens, and its three

pigment-cups may be close together or wide apart and the middle one

rudimentary. As might be expected, in thickened and highly embossed

valves thin spaces occur over the visual organ. The frontal organ

varies in form and apparently in function, and is sometimes absent.

The first antennae, according to the family, may assist in walking,

swimming, burrowing, climbing, grasping, and besides they carry

sensory setae, and sometimes they have suckers on their setae (see

Brady and Norman on _Cypridina norvegica_). The second antennae are

usually the chief motor-organs for swimming, walking and climbing. The

mandibles are normally five-jointed, with remnants of an outer branch

on the second joint, the biting edge varying from strong development

to evanescence, the terminal joints or "palp" giving the organ a

leg-like appearance and function, which disappears in suctorial genera

such as _Paracytherois_. The variable first maxillae are seldom

pediform, their function being concerned chiefly with nutrition,

sensation and respiration. The variability in form and function of the

second maxillae is sufficiently shown by the fact that G.W. Muller,

our leading authority, adopts the confusing plan of calling them

second maxillae in the _Cypridinidae_ (including _Asteropidae_),

maxillipeds in the _Halocypridae_ and _Cyprididae_, and first legs in

the _Bairdiidae_, _Cytheridae_, _Polycopidae_ and _Cytherellidae_, so

that in his fine monograph he uses the term first leg in two quite

different senses. The first legs, meaning thereby the sixth pair of

appendages, are generally pediform and locomotive, but sometimes

unjointed, acting as a kind of brushes to cleanse the furca, while in

the _Polycopidae_ they are entirely wanting. The second legs are

sometimes wanting, sometimes pediform and locomotive, sometimes

strangely metamorphosed into the "vermiform organ," generally long,

many-jointed, and distally armed with retroverted spines, its function

being that of an extremely mobile cleansing foot, which can insert

itself among the eggs in the brood-space, between the branchial leaves

of _Asterope_ (fig. 3), and even range over the external surface of

the valves. The "brush-formed" organs of the Podocopa are medially

placed, and, in spite of their sometimes forward situation, Muller

believes among other possibilities that they and the penis in the

_Cypridinidae_ may be alike remnants of a third pair of legs, not

homologous with the penis of other Ostracoda (Podocopa included). The

furca is, as a rule, a powerful motor-organ, and has its laminae edged

with strong teeth (ungues) or setae or both. The young, though born

with valves, have at first a nauplian body, and pass through various

stages to maturity.

[Illustration: FIG. 2.--_Cythereis ornata_ (G.W. Muller). One

eye-space is shown above on the left.]

[Illustration: FIG. 3.--_Asterope arthuri_. Left valve removed.

M, End of adductor muscle.

OC, Eye.

AI, Second antenna.

MX. 1, First maxilla.

MX. 2, Second maxilla.

P. 1, First foot.

V. O, Vermiform organ.

BR, Seven branchial leaves.

F, Projecting ungues of the furca.]

Brady and Norman, in their _Monograph of the Ostracoda of the North

Atlantic and North-Western Europe_ (1889), give a bibliography of 125

titles, and in the second part (1896) they give 55 more. The lists are

not meant to be exhaustive, any more than G.W. Muller's literature

list of 125 titles in 1894. They do not refer to Latreille, 1802, with

whom the term Ostracoda originates.

COPEPODA.--The body is not encased in a bivalved shell; its articulated

segments are at most eleven, those behind the genital segment being

without trace of limbs, but the last almost always carrying a furca.

Sexes separate, fertilization by spermatophores. Ova in single or double

or rarely several packets, attached as ovisacs or egg-strings to the

genital openings, or enclosed in a dorsal marsupium, or deposited singly

or occasionally in bundles. The youngest larvae are typical nauplii. The

next, the copepodid or cyclopid, stage is characterized by a cylindrical

segmented body, with fore- and hind-body distinct, and by having at most

six cephalic limbs and two pairs of swimming feet.

The order thus defined (see Giesbrecht and Schmeil, _Das Tierreich_,

1898), with far over a thousand species (Hansen, 1900), embraces forms

of extreme diversity, although, when species are known in all their

phases and both sexes, they constantly tend to prove that there are no

sharply dividing lines between the free-living, the semi-parasitic, and

those which in adult life are wholly parasitic and then sometimes

grotesquely unlike the normal standard. Giesbrecht and Hansen have shown

that the mouth-organs consist of mandibles, first and second maxillae

and maxillipeds; and Claus himself relinquished his long-maintained

hypothesis that the last two pairs were the separated exopods and

endopods of a single pair of appendages. Thorell's classification (1859)

of Gnathostoma, Poecilostoma, Siphonostoma, based on the mouth-organs,

was long followed, though almost at the outset shown by Claus to depend

on the erroneous supposition that the Poecilostoma were devoid of

mandibles. Brady added a new section, Choniostomata, in 1894, and

another, Leptostomata, in 1900, each for a single species. Canu in 1892

proposed two groups, Monoporodelphya and Diporodelphya, the copulatory

openings of the female being paired in the latter, unpaired in the

former. It may be questioned whether this distinction, however important

in itself, would lead to a satisfactory grouping of families. In the

same year Giesbrecht proposed his division of the order into Gymnoplea

and Podoplea.

In appearance an ordinary Copepod is divided into fore- and hind-body,

of its eleven segments the composite first being the head, the next five

constituting the thorax, and the last five the abdomen. The coalescence

of segments, though frequent, does not after a little experience

materially confuse the counting. But there is this peculiarity, that the

middle segment is sometimes continuous with the broader fore-body,

sometimes with the narrower hind-body. In the former case the hind-body,

consisting only of the abdomen, forms a pleon or tail-part devoid of

feet, and the species so constructed are Gymnoplea, those of the naked

or footless pleon. In the latter case the middle segment almost always

carries with it to the hind-body a pair of rudimentary limbs, whence the

term Podoplea, meaning species that have a pleon with feet. It may be

objected that hereby the term pleon is used in two different senses,

first applying to the abdomen alone and then to the abdomen plus the

last thoracic segment. Even this verbal flaw would be obviated if

Giesbrecht could prove his tentative hypothesis, that the Gymnoplea may

have lost a pre-genital segment of the abdomen, and the Podoplea may

have lost the last segment of the thorax. The classification is worked

out as follows:--

1. _Gymnoplea._--First segment of hind-body footless, bearing the

orifices of the genital organs (in the male unsymmetrically placed);

last foot of the fore-body in the male a copulatory organ; neither, or

only one, of the first pair of antennae in the male geniculating;

cephalic limbs abundantly articulated and provided with many plumose

setae; heart generally present. Animals usually free-living, pelagic

(Giesbrecht and Schmeil).

This group, with 65 genera and four or five hundred species, is

divided by Giesbrecht into tribes: (a) Amphaskandria. In this tribe

the males have both antennae of the first pair as sensory organs.

There is but one family, the _Calanidae_, but this is a very large

one, with 26 genera and more than 100 species. Among them is the

cosmopolitan _Calanus finmarchicus_, the earliest described (by Bishop

Gunner in 1770) of all the marine free-swimming Copepoda. Among them

also is the peacock Calanid, _Calocalanus pavo_ (Dana), with its

highly ornamented antennae and gorgeous tail, the most beautiful

species of the whole order (fig. 4). (b) Heterarthrandria. Here the

males have one or the other of the first pair of antennae modified

into a grasping organ for holding the female. There are four families,

the _Diaptomidae_ with 27 genera, the _Pontellidae_ with 10, the

_Pseudocyclopidae_ and _Candaciidae_ each with one genus. The first of

these families is often called _Centropagidae_, but, as Sars has

pointed out, _Diaptomus_ (Westwood, 1836) is the oldest genus in it.

Of 177 species valid in the family Giesbrecht and Schmeil assign 67 to

_Diaptomus_. In regard to one of its species Dr Brady says: "In one

instance, at least (Talkin Tarn, Cumberland) I have seen the net come

up from a depth of 6 or 8 ft. below the surface with a dense mass

consisting almost entirely of _D. gracilis_." The length of this

net-filling species is about a twentieth of an inch.

[Illustration: FIG. 4.--_Calocalanus pavo_ (Dana).]

2. _Podoplea._--The first segment of the hind-body almost always with

rudimentary pair of feet; orifices of the genital organs

(symmetrically placed in both sexes) in the following segment; neither

the last foot of the fore-body nor the rudimentary feet just mentioned

acting as a copulatory organ in the male; both or neither of the first

pair of antennae in the male geniculating; cephalic limbs less

abundantly articulated and with fewer plumose setae or none, but with

hooks and clasping setae. Heart almost always wanting. Free-living

(rarely pelagic) or parasitic (Giesbrecht and Schmeil).

This group is also divided by Giesbrecht into two tribes,

Ampharthrandria and Isokerandria. In 1892 he distinguished the former

as those in which the first antennae of the male have both members

modified for holding the female, and the genital openings of the

female have a ventral position, sometimes in close proximity,

sometimes strongly lateral; the latter as those in which the first

antennae of the male are similar to those of the female, the function

of holding her being transferred to the male maxillipeds, while the

genital openings of the female are dorsal, though at times strongly

lateral. In 1899, with a view to the many modifications exhibited by

parasitic and semi-parasitic species, the definitions, stripped of a

too hampering precision, took a different form: (a) Ampharthrandria.

"Swimming Podoplea with geniculating first antennae in the male sex,

and descendants of such; first antennae in female and male almost

always differently articulated." The families occupy fresh water as

well as the sea. Naturally "descendants" which have lost the

characteristic feature of the definition cannot be recognized without

some further assistance than the definition supplies. Of the families

comprised, the _Mormonillidae_ consist only of _Mormonilla_

(Giesbrecht), and are not mentioned by Giesbrecht in 1899 in the

grouping of this section. The _Thaumatoessidae_ include _Thaumatoessa_

(Kroyer), established earlier than its synonym _Thaumaleus_ (Kroyer),

or than _Monstrilla_ (Dana, 1849). The species are imperfectly known.

The defect of mouth-organs probably does not apply to the period of

youth, which some of them spend parasitically in the body-cavity of

worms (Giard, 1896). To the _Cyclopidae_ six genera are allotted by

Giesbrecht in 1900. _Cyclops_ (O.F. Muller, 1776), though greatly

restricted since Muller's time, still has several scores of species

abundantly peopling inland waters of every kind and situation, without

one that can be relied on as exclusively marine like the species of

_Oithona_ (Baird). The _Misophriidae_ are now limited to _Misophria_

(Boeck). The presence of a heart in this genus helps to make it a link

between the Podoplea and Gymnoplea, though in various other respects

it approaches the next family. The _Harpacticidae_ owe their name to

the genus _Arpacticus_ (Milne-Edwards, 1840). Brady in 1880 assigns to

this family 33 genera and 81 species. Canu (1892) distinguishes eight

sub-families, _Longipediinae_, _Peltidiinae_, _Tachidiinae_,

_Amymoninae_, _Harpacticinae_, _Idyinae_, _Canthocamptinae_ (for which

_Canthocampinae_ should be read), and _Nannopinae_, adding

_Stenheliinae_ (Brady) without distinctive characters for it. The

_Ascidicolidae_ have variable characters, showing a gradual adaptation

to parasitic life in Tunicates. Giesbrecht (1900) considers Canu quite

right in grouping together in this single family those parasites of

ascidians, simple and compound, which had been previously distributed

among families with the more or less significant names

_Notodelphyidae_, _Doropygidae_, _Buproridae_, _Schizoproctidae_,

_Kossmechtridae_, _Enterocolidae_, _Enteropsidae_. Further, he

includes in it his own _Enterognathus comatulae_, not from an

ascidian, but from the intestine of the beautiful starfish _Antedon

rosaceus_. The _Asterocheridae_, which have a good swimming capacity,

except in the case of _Cancerilla tubulata_ (Dalyell), lead a

semi-parasitic life on echinoderms, sponges, &c., imbibing their food.

Giesbrecht, displacing the older name _Ascomyzontidae_, assigns to

this family 21 genera in five subfamilies, and suggests that the

long-known but still puzzling _Nicothoe_ from the gills of the lobster

might be placed in an additional subfamily, or be made the

representative of a closely related family. The _Dichelestiidae_, on

account of their sometimes many-jointed first antennae, are referred

also to this tribe by Giesbrecht. (b) Isokerandria. "Swimming Podoplea

without genicullating first antennae in the male sex, and descendants

of such. First antennae of male and female almost always articulated

alike." To this tribe Giesbrecht assigns the families _Clausidiidae_,

_Corycaeidae_, _Oncaeidae_, _Lichomolgidae_, _Ergasilidae_,

_Bomolochidae_, _Clausiidae_, _Nereicolidae_. Here also must for the

time be placed the _Caligidae_, _Philichthyidae_ (_Philichthydae_ of

Vogt, Carus, Claus), _Lernaeidae_, _Chondracanthidae_,

_Sphaeronellidae_ (better known as _Choniostomatidae_, from H.J.

Hansen's remarkable study of the group), _Lernaeopodidae_,

_Herpyllobiidae_, _Entomolepidae_. For the distinguishing marks of all

these, the number of their genera and species, their habits and

transformations and dwellings, the reader must be referred to the

writings of specialists. Sars (1901) proposed seven

suborders--Calanoida, Harpacticoida, Cyclopoida, Notodelphoida,

Monstrilloida, Caligoida, Lernaeoida.

AUTHORITIES.--(The earlier memoirs of importance are cited in

Giesbrecht's _Monograph of Naples_, 1892); Canu, "Hersiliidae," _Bull.

Sci. France belgique_, ser. 3, vol. i. p. 402 (1888); and _Les

Copepodes du Boulonnais_ (1892); Cuenot, _Rev. biol. Nord France_,

vol. v. (1892); Giesbrecht, "Pelag. Copepoden." _F. u. fl. des Golfes

von Neapel_ (Mon. 19, 1892); Hansen, _Entomol. Med._ vol. iii. pt. 5

(1892); I.C. Thompson, "Copepoda of Liverpool Bay," _Trans. Liv. Biol.

Soc._ vol. vii. (1893); Schmeil, "Deutschlands Copepoden,"

_Bibliotheca zoologica_ (1892-1897); Brady, _Journ. R. Micr. Soc._ p.

168 (1894); T. Scott, "Entomostraca from the Gulf of Guinea," _Trans.

Linn. Soc. London_, vol. vi. pt. 1 (1894); Giesbrecht, _Mitteil. Zool.

Stat. Neapel_, vol. xi. p. 631; vol. xii. p. 217 (1895); T. and A.

Scott, _Trans. Linn. Soc. London_, ser. 2, vol. vi. p. 419 (1896);

Hansen "Choniostomatidae" (1897); Sars, _Proc. Mus. Zool. St

Petersburg_, "Caspian Entomostraca" (1897); Giesbrecht and Schmeil,

"Copepoda gymnoplea," _Das Tierreich_ (1898); Giesbrecht,

"Asterocheriden," _F. u. fl. Neapel_ (Mon. 25, 1899); Bassett-Smith,

"Copepoda on Fishes," _Proc. Zool. Soc. London_, p. 438 (1899); Brady,

_Trans. Zool. Soc. London_, vol. xv. pt. 2, p. 31 (1899); Sars, _Arch.

Naturv._ vol. xxi. No. 2 (1899); Giesbrecht, _Mitteil. Zool. Stat.

Neapel_, vol. xiv. p. 39 (1900); Scott, "Fish Parasites," _Scottish

Fishery Board_, 18th Ann. Rep. p. 144 (1900); Stebbing, _Willey's

Zool. Results_, pt. 5, p. 664 (1900); Embleton, _Journ. Linn. Soc.

London_, vol. xxviii. p. 211 (1901); Sars, _Crustacea of Norway_, vol.

iv. (1901). (T. R. R. S.)

ENTRAGUES, CATHERINE HENRIETTE DE BALZAC D' (1579-1633), marquise de

Verneuil, mistress of Henry IV., king of France, was the daughter of

Charles Balzac d'Entragues and of Marie Touchet, mistress of Charles IX.

Ambitious and intriguing, she succeeded in inducing Henry IV. to promise

to marry her after the death of Gabrielle d'Estrees, a promise which led

to bitter scenes at court when shortly afterwards Henry married Marie

de' Medici. She carried her spite so far as to be deeply compromised in

the conspiracy of Marshal Biron against the king in 1606, but escaped

with a slight punishment, and in 1608 Henry actually took her back into

favour again. She seems then to have been involved in the Spanish

intrigues which preceded the death of the king in 1610.

See H. de la Ferriere, _Henri IV. le roi, l'amoureux_ (Paris, 1890).

ENTRECASTEAUX, JOSEPH-ANTOINE BRUNI D' (1739-1793), French navigator,

was born at Aix in 1739. At the age of fifteen he entered the navy. In

the war of 1778 he commanded a frigate of thirty-two guns, and by his

clever seamanship was successful in convoying a fleet of merchant

vessels from Marseilles to the Levant, although they were attacked by

two pirate vessels, each of which was larger than his own ship. In 1785

he was appointed to the command of the French fleet in the East Indies,

and two years later he was named governor of the Mauritius and the Isle

of Bourbon. While in command of the East India fleet he made a voyage to

China, an achievement which, in 1791, led the French government to

select him to command an expedition which it was sending out to seek

some tidings of the unfortunate La Perouse, of whom nothing had been

heard since February 1788. Rear-admiral d'Entrecasteaux's expedition

comprised the "Recherche" and "L'Esperance," with Captain Huon de

Kermadec as second in command. No tidings were obtained of the missing

navigator, but in the course of his search Entrecasteaux made important

geographical discoveries. He traced the outlines of the eastern coast of

New Caledonia, made extensive surveys round the Tasmanian coast, and

touched at several places on the south coast of New Holland. The two

ships entered Storm Bay, Tasmania, on the 21st of April 1792, and

remained there until the 16th of May, surveying and naming the

d'Entrecasteaux Channel, the entrances to the Huon and Derwent rivers,

Bruni Island, Recherche Bay, Port Esperance and various other

localities. Excepting the name of the river Derwent (originally called

Riviere du Nord by its French discoverers), these foregoing appellations

have been retained. Leaving Tasmania the expedition sailed northward for

the East Indies, and while coasting near the island of Java,

Entrecasteaux was attacked by scurvy and died on the 20th of July 1793.

ENTRE MINHO E DOURO (popularly called _Minho_), a former province of

Northern Portugal; bounded on the N. by Galicia in Spain, E. by

Traz-os-Montes, S. by Beira and W. by the Atlantic Ocean. Pop. (1900)

1,170,361; area 2790 sq. m. Though no longer officially recognized, the

old provincial name remains in common use. The coast-line of Entre Minho

e Douro is level and unbroken except by the estuaries of the main

rivers; inland, the elevation gradually increases towards the north and

east, where several mountain ranges mark the frontier. Of these, the

most important are the Serra da Peneda (4728 ft.), between the rivers

Minho and Limia; the Serra do Gerez (4357 ft.), on the Galician border;

the Serra da Cabreira (4021 ft.), immediately to the south; and the

Serra de Marao (4642 ft.), in the extreme south-east. As its name

implies, the province is bounded by two great rivers, the Douro (q.v.)

on the south, and the Minho (Spanish _Mino_) on the north; but a small

tract of land south of the Douro estuary is included also within the

provincial boundary. There are three other large rivers which, like the

Minho, flow west-south-west into the Atlantic. The Limia or Antela

(Spanish _Linia_) rises in Galicia, and reaches the sea at Vianna do

Castello; the Cavado springs from the southern foot hills of La Raya

Seca, on the northern frontier of Traz-os-Montes, and forms, at its

mouth, the small harbour of Espozende; and the Ave descends from its

sources in the Serra da Cabreira to Villa do Conde, where it enters the

Atlantic. A large right-hand tributary of the Douro, the Tamega, rises

in Galicia, and skirts the western slopes of the Serra de Marao.

The climate is mild, except among the mountains, and such plants as

heliotrope, fuchsias, palms, and aloes thrive in the open throughout the

year. Wheat and maize are grown on the plains, and other important

products are wine, fruit, olives and chestnuts. Fish abound along the

coast and in the main rivers; timber is obtained from the mountain

forests, and dairy-farming and the breeding of pigs and cattle are

carried on in all parts. As the province is occupied by a hardy and

industrious peasantry, and the density of population (419.5 per sq. m.)

is more than twice that of any other province on the Portuguese

mainland, the soil is very closely cultivated. The methods and

implements of the farmers are, however, most primitive, and at the

beginning of the 20th century it was not unusual to see a mule, or even

a woman, harnessed with the team of oxen to an old-fashioned wooden

plough. Small quantities of coal, iron, antimony, lead and gold are

mined; granite and slate are quarried; and there are mineral springs at

Moncao (pop. 2283) on the Minho. The Oporto-Corunna railway traverses

the western districts and crosses the Spanish frontier at Tuy; its

branch lines give access to Braga, Guimaraes and Povoa de Varzim; and

the Oporto-Salamanca railway passes up the Douro valley. The greater

part of the north and west can only be reached by road, and even the

chief highways are ill-kept. In these regions the principal means of

transport is the springless wooden cart, drawn by one or more of the

tawny and under-sized but powerful oxen, with immense horns and

elaborately carved yoke, which are characteristic of northern Portugal.

For administrative purposes the province is divided into three

districts: Vianna do Castello in the north, Braga in the centre, Oporto

in the south. The chief towns are separately described; they include

Oporto (167,955), one of the greatest wine-producing cities in the

world; Braga (24,202), the seat of an archbishop who is primate of

Portugal; the seaports of Povoa de Varzim (12,623) and Vianna do

Castello (9990); and Guimaraes (9104), a place of considerable

historical interest.

ENTREPOT (a French word, from the Lat. _interpositum_, that which is

placed between), a storehouse or magazine for the temporary storage of

goods, provisions, &c.; also a place where goods, which are not allowed

to pass into a country duty free, are stored under the superintendence

of the custom house authorities till they are re-exported. In a looser

sense, any town which has a considerable distributive trade is called an

_entrepot_. The word is also used attributively to indicate the kind of

trade carried on in such towns.

ENTRE RIOS (Span. "between rivers"), a province of the eastern Argentine

Republic, forming the southern part of a region sometimes described as

the Argentine Mesopotamia, bounded N. by Corrientes, E. by Uruguay with

the Uruguay river as the boundary line, S. by Buenos Aires and W. by

Santa Fe, the Parana river forming the boundary line with these two

provinces. Pop. (1895) 292,019; (1905, est.) 376,600. The province has

an area of 28,784 sq. m., consisting for the most part of an undulating,

well-watered and partly-wooded plain, terminating in a low, swampy

district of limited extent in the angle between the two great rivers.

The great forest of Monteil occupies an extensive region in the N.,

estimated at nearly one-fifth the area of the province. Its soil is

exceptionally fertile and its climate is mild and healthy. The province

is sometimes called the "garden of Argentina," which would probably be

sufficiently correct had its population devoted as much energy to

agriculture as they have to political conflict and civil war. Its

principal industry is that of stock-raising, exporting live cattle,

horses, hides, jerked beef, tinned and salted meats, beef extract,

mutton and wool. Its agricultural products are also important, including

wheat, Indian corn, barley and fruits. Lime, gypsum and firewood are

also profitable items in its export trade. The Parana and Uruguay rivers

provide exceptional facilities for the shipment of produce and the Entre

Rios railways, consisting of a trunk line running E. and W. across the

province from Parana to Concepcion del Uruguay and several tributary

branches, afford ample transportation facilities to the ports. Another

railway line follows the Uruguay from Concordia northward into

Corrientes. Entre Rios has been one of the most turbulent of the

Argentine provinces, and has suffered severely from political disorder

and civil war. Comparative quiet reigned from 1842 to 1870 under the

autocratic rule of Gen. J.J. Urquiza. After his assassination in 1870

these partizan conflicts were renewed for two or three years, and then

the province settled down to a life of comparative peace, followed by an

extraordinary development in her pastoral and agricultural industries.

Among these is the slaughtering and packing of beef, the exportation of

which has reached large proportions. The capital is Parana, though the

seat of government was originally located at Concepcion del Uruguay, and

was again transferred to that town during Urquiza's domination.

Concepcion del Uruguay, or Concepcion (founded 1778), is a flourishing

town and port on the Uruguay, connected by railway with an extensive

producing region which gives it an important export trade, and is the

seat of a national college and normal school. Its population was

estimated at 9000 in 1905. Other large towns are Gualeguay and

Gualeguaychu.

ENVOY (Fr. _envoye_, "sent"), a diplomatic agent of the second rank. The

word _envoye_ comes first into general use in this connexion in the 17th

century, as a translation of the Lat. _ablegatus_ or _missus_ (see

DIPLOMACY). Hence the word envoy is commonly used of any one sent on a

mission of any sort.

ENZIO (c. 1220-1272), king of Sardinia, was a natural son of the

emperor Frederick II. His mother was probably a German, and his name,

Enzio, is a diminutive form of the German _Heinrich_. His father had a

great affection for him, and he was probably present at the battle of

Cortenuova in 1237. In 1238 he was married, in defiance of the wishes of

Pope Gregory IX., to Adelasia, widow of Ubaldo Visconti and heiress of

Torres and Gallura in Sardinia. Enzio took at once the title of king of

Torres and Gallura, and in 1243 that of king of Sardinia, but he only

spent a few months in the island, and his sovereignty existed in name

alone. In July 1239 he was appointed imperial vicegerent in Italy, and

sharing in his father's excommunication in the same year, took a

prominent part in the war which broke out between the emperor and the

pope. He commenced his campaign by subduing the march of Ancona, and in

May 1241 was in command of the forces which defeated the Genoese fleet

at Meloria, where he seized a large amount of booty and captured a

number of ecclesiastics who were proceeding to a council summoned by

Gregory to Rome. Later he fought in Lombardy. In 1248 he assisted

Frederick in his vain attempt to take Parma, but was wounded and taken

prisoner by the Bolognese at Fossalta on the 26th of May 1249. His

captivity was a severe blow to the Hohenstaufen cause in Italy, and was

soon followed by the death of the emperor. He seems to have been well

treated by the people of Bologna, where he remained a captive until his

death on the 14th of March 1272. He was apparently granted a magnificent

funeral, and was buried in the church of St Dominic at Bologna. During

his imprisonment Enzio is said to have been loved by Lucia da Viadagola,

a well-born lady of Bologna, who shared his captivity and attempted to

procure his release. Some doubt has, however, been cast upon this story,

and the same remark applies to another which tells how two friends had

almost succeeded in freeing him from prison concealed in a wine-cask,

when he was recognized by a lock of his golden hair. His marriage with

Adelasia had been declared void by the pope in 1243, and he left one

legitimate, and probably two illegitimate daughters. Enzio forms the

subject of a drama by E.B.S. Raupach and of an opera by A.F.B. Dulk.

See F.W. Grossman, _Konig Enzio_ (Gottingen, 1883); and H. Blasius,

_Konig Enzio_ (Breslau, 1884).

ENZYME (Gr. [Greek: enzymos], leavened, from [Greek: en], in, and

[Greek: zyme], leaven), a term, first suggested by Kuhne, for an

unorganized ferment (see FERMENTATION), a group of substances, in the

constitution of plants and animals, which decompose certain carbon

compounds occurring in association with them. See also PLANTS:

_Physiology_; NUTRITION, &c.

EOCENE (Gr. [Greek: eos], dawn, [Greek: kainos], recent), in geology,

the name suggested by Sir C. Lyell in 1833 for the lower subdivision of

the rocks of the Tertiary Era. The term was intended to convey the idea

that this was the period which saw the dawn of the recent or existing

forms of life, because it was estimated that among the fossils of this

period only 3-1/2% of the species are still living. Since Lyell's time

much has been learned about the fauna and flora of the period, and many

palaeontologists doubt if any of the Eocene _species_ are still extant,

unless it be some of the lowest forms of life. Nevertheless the name is

a convenient one and is in general use. The Eocene as originally defined

was not long left intact, for E. Beyrich in 1854 proposed the term

"Oligocene" for the upper portion, and later, in 1874, K. Schimper

suggested "Paleocene" as a separate appellation for the lower portion.

The Oligocene division has been generally accepted as a distinct period,

but "Paleocene" is not so widely used.

In north-western Europe the close of the Cretaceous period was marked

by an extensive emergence of the land, accompanied, in many places, by

considerable erosion of the Mesozoic rocks; a prolonged interval elapsed

before a relative depression of the land set in and the first Eocene

deposits were formed. The early Eocene formations of the

London-Paris-Belgian basin were of fresh-water and brackish origin;

towards the middle of the period they had become marine, while later

they reverted to the original type. In southern and eastern Europe

changes of sea-level were less pronounced in character; here the late

Cretaceous seas were followed without much modification by those of the

Eocene period, so rich in foraminiferal life. In many other regions, the

great gap which separates the Tertiary from the Mesozoic rocks in the

neighbourhood of London and Paris does not exist, and the boundary line

is difficult to draw. Eocene strata succeed Cretaceous rocks without

serious unconformity in the Libyan area, parts of Denmark, S.E. Alps,

India, New Zealand and central N. America. The unconformity is marked in

England, parts of Egypt, on the Atlantic coastal plain and in the

eastern gulf region of N. America, as well as in the marine Eocene of

western Oregon. The clastic Flysch formation of the Carpathians and

northern Alps appears to be of Eocene age in the upper and Cretaceous in

the lower part. The Eocene sea covered at various times a strip of the

Atlantic coast from New Jersey southward and sent a great tongue or bay

up the Mississippi valley; similar epicontinental seas spread over parts

of the Pacific border, but the plains of the interior with the mountains

on the west were meanwhile being filled with terrestrial and lacustrine

deposits which attained an enormous development. This great extension of

non-marine formations in the Eocene of different countries has

introduced difficulties in the way of exact correlation; it is safer,

therefore, in the present state of knowledge, to make no attempt to find

in the Eocene strata of America and India, &c., the precise equivalent

of subdivisions that have been determined with more or less exactitude

in the London-Paris-Belgian area.

[Illustration: Distribution of Eocene Rocks.]

It is possible that in Eocene times there existed a greater continuity

of the northern land masses than obtains to-day. Europe at that time was

probably united with N. America through Iceland and Greenland; while on

the other side, America may have joined Asia by the way of Alaska. On

the other hand, the great central, mediterranean sea which stretched

across the Eurasian continents sent an arm northward somewhere just east

of the Ural mountains, and thus divided the northern land mass in that

region. S. America, Australia and perhaps Africa _may_ have been

connected more or less directly with the Antarctic continent.

Associated, no doubt, with the crustal movements which closed the

Cretaceous and inaugurated the Eocene period, there were local and

intermittent manifestations of volcanic activity throughout the period.

Diabases, gabbros, serpentines, soda-potash granites, &c., are found in

the Eocene of the central and northern Apennines. Tuffs occur in the

Veronese and Vicentin Alps--Ronca and Spelecco schists. Tuffs, basalts

and other igneous rocks appear also in Montana, Wyoming, California,

Oregon, Washington, Idaho, Colorado; also in Central America, the

Antillean region and S. America.

It has been very generally assumed by geologists, mainly upon the

evidence of plant remains, that the Eocene period opened with a

temperate climate in northern latitudes; later, as indicated by the

London Clay, Alum Bay and Bournemouth beds, &c., the temperature appears

to have been at least subtropical. But it should be observed that the

frequent admixture of temperate forms with what are now tropical species

makes it difficult to speak with certainty as to the degree of warmth

experienced. The occurrence of lignites in the Eocene of the Paris

basin, Tirol and N. America is worthy of consideration in this

connexion. On the other hand, the coarse boulder beds in the lower

Flysch have been regarded as evidence of local glaciation; this would

not be inconsistent with a period of widespread geniality of climate, as

is indicated by the large size of the nummulites and the dispersion of

the marine Mollusca, but the evidence for glaciation is not yet

conclusive.

_Eocene Stratigraphy._--In Britain, with the exception of the Bovey

beds (q.v.) and the leaf-bearing beds of Antrim and Mull, Eocene rocks

are confined to the south-eastern portion of England. They lie in the

two well-marked synclinal basins of London and Hampshire which are

conterminous in the western area (Hampshire, Berkshire), but are

separated towards the east by the denuded anticline of the Weald. The

strata in these two basins have been grouped in the following manner:--

_London Basin._ _Hampshire Basin._

Upper Upper Bagshot Sands. Headon Hill and Barton Sands.

/ Middle Bagshot Beds and Bracklesham Beds and leaf

Middle < part of Lower Bagshot beds of Bournemouth and

\ Beds. Alum Bay.

/ Part of Lower Bagshot

| Beds, London Clay,

| Blackheath and Oldhaven London Clay and the equivalent

Lower < Beds, Woolwich and Bognor Beds, Woolwich

| Reading Beds, Thanet and Reading Beds.

\ Sands.

The Thanet sands have not been recognized in the Hampshire basin; they

are usually pale yellow and greenish sands with streaks of clay and at

the base; resting on an evenly denuded surface of chalk is a very

constant layer of green-coated, well-rounded chalk flint pebbles. It

is a marine formation, but fossils are scarce except in E. Kent, where

it attains its most complete development. The Woolwich and Reading

beds (see READING BEDS) contain both marine and estuarine fossils. In

western Kent, between the Woolwich beds and the London Clay are the

Oldhaven beds or Blackheath pebbles, 20 to 40 ft., made up almost

entirely of well-rounded flint pebbles set in sand; the fossils are

marine and estuarine. The London Clay, 500 ft. thick, is a marine

deposit consisting of blue or brown clay with sandy layers and

septarian nodules; its equivalent in the Hampshire area is sometimes

called the Bognor Clay, well exposed on the coast of Sussex. The

Bagshot, Bracklesham and Barton beds will be found briefly described

under those heads.

Crossing the English Channel, we find in northern France and Belgium a

series of deposits identified in their general characters with those

of England. The anticlinal ridge of the English Weald is prolonged

south-eastwards on to the continent, and separates the Belgian from

the French Eocene areas much as it separates the areas of London and

Hampshire; and it is clear that at the time of deposition all four

regions were intimately related and subject to similar variations of

marine and estuarine conditions. With a series of strata so variable

from point to point it is natural that many purely local phases should

have received distinctive names; in the Upper Eocene of the Paris

basin the more important formations are the highly fossiliferous

marine sands known as the "Sands of Beauchamp" and the local

fresh-water limestone, the "Calcaire de St Ouen." The Middle Eocene is

represented by the well-known "Calcaire grossier," about 90 ft. thick.

The beds in this series vary a good deal lithologically, some being

sandy, others marly or glauconitic; fossils are abundant. The Upper

Calcaire grossier or "Caillasses" is a fresh-water formation; the

middle division is marine; while the lower one is partly marine,

partly of fresh-water origin. The numerous quarries and mines for

building stone in the neighbourhood of Paris have made it possible to

acquire a very precise knowledge of this division, and many of the

beds have received trade names, such as "Rochette," "Roche," "Banc

franc," "Banc vert," "Cliquart," "Saint Nom;" the two last named are

dolomitic. Below these limestones are the nummulitic sands of Cuise

and Soissons. The Lower Eocene contains the lignitic plastic clay

(_argile plastique_) of Soissons and elsewhere; the limestones of

Rilly and Sezanne and the greenish glauconitic sands of Bracheux. The

relative position of the above formations with respect to those of

Belgium and England will be seen from the table of Eocene strata. The

Eocene deposits of southern Europe differ in a marked manner from

those of the Anglo-Parisian basin. The most important feature is the

great development of nummulitic limestone with thin marls and

nummulitic sandstones. The sea in which the nummulitic limestones were

formed occupied the site of an enlarged Mediterranean communicating

with similar waters right round the world, for these rocks are found

not only in southern Europe, including all the Alpine tracts, Greece

and Turkey and southern Russia, but they are well developed in

northern Africa, Asia Minor, Palestine, and they may be followed

through Persia, Baluchistan, India, into China, Tibet, Japan, Sumatra,

Borneo and the Philippines. The nummulitic limestones are frequently

hard and crystalline, especially where they have been subjected to

elevation and compression as in the Alpine region, 10,000 ft. above

the sea, or from 16,000, to 20,000 ft., in the central Asian plateau.

Besides being a widespread formation the nummulitic limestone is

locally several thousand feet thick.

While the foraminiferal limestones were being formed over most of

southern Europe, a series of clastic beds were in course of formation

in the Carpathians and the northern Alpine region, viz. the Flysch and

the Vienna sandstone. Some portions of this Alpine Eocene are coarsely

conglomeratic, and in places there are boulders of non-local rocks of

enormous dimensions included in the argillaceous or sandy matrix. The

occurrence of these large boulders together with the scarceness of

fossils has suggested a glacial origin for the formation; but the

evidence hitherto collected is not conclusive. C.W. von Gumbel has

classified the Eocene of the northern Alps (Bavaria, &c.) as follows:--

Upper Eocene, Flysch and Vienna sandstone, with younger nummulitic

beds and Haring group.

Middle " Kressenberg Beds, with older nummulitic beds.

Lower " Burberg Beds, Greensands with small nummulites.

The Haring group of northern Tirol contains lignite beds of some

importance. In the southern and S.E. Alps the following divisions are

recognized.

Upper Eocene, Macigno or Tassello--Vienna Sandstone, conglomerates,

marls and shales.

Middle " Nummulitic limestones, three subdivisions.

Lower " Liburnian stage (or Proteocene), foraminiferal

limestones with fresh-water intercalations at the top

and bottom, the _Cosina_ beds, fresh-water in the

middle of the series.

In the central and northern Apennines the Eocene strata have been

subdivided by Prof. F. Sacco into an upper Bartonian, a middle

Parisian and a lower Suessonian series. In the middle member are the

representatives of the Flysch and the Macigno. These Eocene strata are

upwards of 5500 ft. thick. In northern Africa the nummulitic

limestones and sandstones are widely spread; the lower portions

comprise the Libyan group and the shales of Esneh on the Nile

(Flandrien), the _Alveolina_ beds of Sokotra and others; the Mokattam

stage of Egypt is a representative of the later Eocene. Much of the N.

African Eocene contains phosphatic beds. In India strata of Eocene age

are extensively developed; in Sind the marine Ranikot beds, 1500 to

2000 ft., consisting of clays with gypsum and lignite, shales and

sandstones; these beds have, side by side with Eocene nummulites, a

few fossils of Cretaceous affinities. Above the Ranikot beds are the

massive nummulitic limestones and sandstones of the Kirthar group;

these are succeeded by the nummulitic limestones and shales at the

base of the Nari group. In the southern Himalayan region the

nummulitic phase of Eocene deposit is well developed, but there are

difficulties in fixing the line of demarcation between this and the

younger formations. The lower part of the Sirmur series of the Simla

district may belong to this period; it is subdivided into the Kasauli

group and the Dagshai group with the Subathu group at the base.

Beneath the thick nummulitic Eocene limestone of the Salt Range are

shales and marls with a few coal seams. The marine Eocene rocks of N.

America are most extensively developed round the coast of the Gulf of

Mexico, whence they spread into the valley of the Mississippi and, as

a comparatively narrow strip, along the Atlantic coastal plain to New

Jersey.

The series in Alabama, which may be taken as typical of the Gulf coast

Eocene, is as follows:--

Upper Jacksonian, White limestone of Alabama (and Vicksburg?).

Middle Claibornian, Claiborne series.

Buhrstone series.

Lower, Chickasawan Sands and lignites.

Midwayan or Clayton formation, limestones.

The above succession is not fully represented in the Atlantic coast

states.

On the Pacific coast marine formations are found in California and

Oregon; such are the Tejon series with lignite and oil; the Escondido

series of S. California (7000 ft.), part of the Pascadero series of

the Santa Cruz Mountains; the Pulaski, Tyee, Arago and Coaledo

beds--with coals--in Oregon. In the Puget formation of Washington we

have a great series of sediments, largely of brackish water origin,

and in parts coal-bearing. The total thickness of this formation has

been estimated at 20,000 ft. (it may prove to be less than this), but

it is probable that only the lower portion is of Eocene age. The most

interesting of the N. American Eocene deposits are those of the Rocky

Mountains and the adjacent western plains, in Wyoming, Nevada,

Nebraska, Colorado, &c.; they are of terrestrial, lacustrine or

aeolian origin, and on this account and because they were not strictly

synchronous, there is considerable difficulty in placing them in their

true position in the time-scale. The main divisions or groups are

generally recognized as follows:--

Mammalian

Zonal Forms.

Upper [1] Uinta Group, 800 ft. (? = Jacksonian) _Diplacodon._

_Telmatotherium._