DISPERSION OF FRESH-WATER FISHES[63]
=Dispersion of Fishes.=--The methods of dispersion of fishes may be
considered apart from the broader topic of distribution or the final
results of such dispersion. In this discussion we are mainly concerned
with the fresh-water fishes, as the methods of distribution of marine
fishes through marine currents and by continuity of shore and water
ways are all relatively simple.
=The Problem of Oatka Creek.=--When I was a boy and went fishing in
the brooks of western New York, I noticed that the different streams
did not always have the same kinds of fishes in them. Two streams in
particular in Wyoming County, not far from my father's farm, engaged in
this respect my special attention. Their sources are not far apart, and
they flow in opposite directions, on opposite sides of a low ridge--an
old glacial moraine, something more than a mile across. The Oatka Creek
flows northward from this ridge, while the East Coy runs toward the
southeast on the other side of it, both flowing ultimately into the
same river, the Genesee.
It does not require a very careful observer to see that in these two
streams the fishes are not quite the same. The streams themselves
are similar enough. In each the waters are clear and fed by springs.
Each flows over gravel and clay, through alluvial meadows, in many
windings, and with elms and alders "in all its elbows." In both streams
we were sure of finding trout,[64] and in one of them the trout are
still abundant. In both we used to catch the brook chub,[65] or, as
we called it, the "horned dace"; and in both were large schools of
shiners[66] and of suckers.[67] But in every deep hole, and especially
in the millponds along the East Coy Creek, the horned pout[68] swarmed
on the mucky bottoms. In every eddy, or in the deep hole worn out at
the root of the elm-trees, could be seen the sunfish,[69] strutting
in green and scarlet, with spread fins keeping intruders away from
its nest. But in the Oatka Creek were found neither horned pout nor
sunfish, nor have I ever heard that either has been taken there. Then
besides these nobler fishes, worthy of a place on every schoolboy's
string, we knew by sight, if not by name, numerous smaller fishes,
darters[70] and minnows,[71] which crept about in the gravel on the
bottom of the East Coy, but which we never recognized in the Oatka.
There must be a reason for differences like these, in the streams
themselves or in the nature of the fishes. The sunfish and the horned
pout are home-loving fishes to a greater extent than the others which
I have mentioned; still, where no obstacles prevent, they are sure to
move about. There must be, then, in the Oatka some sort of barrier,
or strainer, which keeping these species back permits others more
adventurous to pass; and a wider knowledge of the geography of the
region showed that such is the case. Farther down in its course, the
Oatka falls over a ledge of rock, forming a considerable waterfall at
Rock Glen. Still lower down its waters disappear in the ground, sinking
into some limestone cavern or gravel-bed, from which they reappear,
after some six miles, in the large springs at Caledonia. Either of
these barriers might well discourage a quiet-loving fish; while the
trout and its active associates have some time passed them, else we
should not find them in the upper waters in which they alone form the
fish fauna. This problem is a simple one; a boy could work it out, and
the obvious solution seems to be satisfactory.
=Generalizations as to Dispersion.=--Since those days I have been a
fisherman in many waters,--not an angler exactly, but one who fishes
for fish, and to whose net nothing large or small ever comes amiss; and
wherever I go I find cases like this.
We do not know all the fishes of America yet, nor all those well
that we know by sight; still this knowledge will come with time and
patience, and to procure it is a comparatively easy task. It is also
easy to ascertain the more common inhabitants of any given stream. It
is difficult, however, to obtain negative results which are really
results. You cannot often say that a species does not live in a
certain stream. You can only affirm that you have not yet found it
there, and you can rarely fish in any stream so long that you can find
nothing that you have not taken before. Still more difficult is it to
gather the results of scattered observations into general statements
regarding the distribution of fishes. The facts may be so few as to be
misleading, or so numerous as to be confusing, and the few writers who
have taken up this subject in detail have found both these difficulties
to be serious. Whatever general propositions we may maintain must be
stated with the modifying clause of "other things being equal"; and
other things are never quite equal. The saying that "Nature abhors a
generalization" is especially applicable to all discussions of the
relations of species to environment.
Still less satisfactory is our attempt to investigate the causes on
which our partial generalizations depend,--to attempt to break to
pieces the "other things being equal" which baffle us in our search
for general laws. The same problems, of course, come up on each of
the other continents and in all groups of animals or plants; but most
that I shall say will be confined to the question of the dispersion
of fishes in the fresh waters of North America. The broader questions
of the boundaries of faunæ and of faunal areas I shall bring up only
incidentally.
=Questions Raised by Agassiz.=--Some of the problems to be solved were
first noticed by Prof. Agassiz in 1850, in his work on Lake Superior.
Later (1854), in a paper on the fishes of the Tennessee River,[72] he
makes the following statement:
"The study of these features [of distribution] is of the greatest
importance, inasmuch as it may eventually lead to a better
understanding of the intentions implied in this seemingly arbitrary
disposition of animal life....
"There is still another very interesting problem respecting the
geographical distribution of our fresh-water animals which may be
solved by the further investigation of the fishes of the Tennessee
River. The water-course, taking the Powell, Clinch, and Holston Rivers
as its head waters, arises from the mountains of Virginia in latitude
37°; it then flows S.W. to latitude 34° 25', when it turns W. and N.W.,
and finally empties into the Ohio, under the same latitude as its
source in 37°.
[Illustration: FIG. 185.--Horned Dace, _Semotilus atromaculatus_
(Mitchill). Aux Plaines River, Ills. Family _Cyprinidæ_.]
"The question now is this: Are the fishes of this water system the
same throughout its extent? In which case we should infer that water
communication is the chief condition of geographical distribution of
our fresh-water fishes. Or do they differ in different stations along
its course? And if so, are the differences mainly controlled by the
elevation of the river above the level of the sea, or determined by
climatic differences corresponding to differences of latitude? We
should assume that the first alternative was true if the fishes of the
upper course of the river differed from those of the middle and lower
courses in the same manner as in the Danube, from its source to Pesth,
where this stream flows nearly for its whole length under the same
parallel. We would, on the contrary, suppose the second alternative
to be well founded if marked differences were observed between the
fish of such tracts of the river as do not materially differ in their
evolution above the sea, but flow under different latitudes. Now, a few
collections from different stations along this river, like that sent
me by Dr. Newman from the vicinity of Huntsville, would settle at once
this question, not for the Tennessee River alone, but for most rivers
flowing under similar circumstances upon the surface of the globe.
Nothing, however, short of such collections, compared closely with one
another, will furnish a reliable answer.... Whoever will accomplish
this survey will have made a highly valuable contribution to our
knowledge."
=Conclusions of Cope.=--Certain conclusions were also suggested by
Prof. Cope in his excellent memoir on the fishes of the Alleghany
region[73] in 1868. From this paper I make the following quotations:
"The distribution of fresh-water fishes is of special importance to the
questions of the origin and existence of species in connection with the
physical conditions of the waters and of the land. This is, of course,
owing to the restricted nature of their habitat and the impossibility
of their making extended migrations. With the submergence of land
beneath the sea, fresh-water fish are destroyed in proportion to the
extent of the invasion of salt water, while terrestrial vertebrates can
retreat before it. Hence every inland fish fauna dates from the last
total submergence of the country.
"Prior to the elevation of a given mountain chain, the courses of the
rivers may generally have been entirely different from their later
ones. Subsequent to this period, they can only have undergone partial
modifications. As subsequent submergences can rarely have extended to
the highlands where such streams originate, the fishes of such rivers
can only have been destroyed so far as they were unable to reach those
elevated regions, and preserve themselves from destruction from salt
water by sheltering themselves in mountain streams. On the other hand,
a period of greater elevation of the land, and of consequent greater
cold, would congeal the waters and cover their courses with glaciers.
The fishes would be driven to the neighborhood of the coast, though no
doubt in more southern latitudes a sufficient extent of uncongealed
fresh waters would flow by a short course into the ocean, to preserve
from destruction many forms of fresh-water fishes. Thus, through many
vicissitudes, the fauna of a given system of rivers has had opportunity
of uninterrupted descent, from the time of the elevation of the
mountain range, in which it has its sources....
"As regards the distinction of species in the disconnected basins of
different rivers, which have been separated from an early geologic
period, if species occur which are common to any two or more of them,
the supporter of the theory of distinct creations must suppose that
such species have been twice created, once for each hydrographic basin,
or that waters flowing into the one basin have been transferred to
another. The developmentalist, on the other hand, will accept the last
proposition, or else suppose that time has seen an identical process
and similar result of modification in these distinct regions.
[Illustration: FIG. 186.--Chub of the Great Basin, _Leuciscus lineatus_
(Girard). Heart Lake, Yellowstone Park. Family _Cyprinidæ_.]
"Facts of distribution in the eastern district of North America are
these. Several species of fresh-water fishes occur at the same time
in many Atlantic basins from the Merrimac or from the Hudson to the
James, and throughout the Mississippi Valley, and in the tributaries of
the Great Lakes. On the other hand, the species of each river may be
regarded as pertaining to four classes, whose distribution has direct
reference to the character of the water and the food it offers: first,
those of the tide-waters, of the river channels, bayous, and sluggish
waters near them, or in the flat lands near the coast; second, those of
the river channels of its upper course, where the currents are more
distinct; third, those of the creeks of the hill country; fourth, those
of the elevated mountain streams which are subject to falls and rapids."
In the same paper Prof. Cope reaches two important general conclusions,
thus stated by him:
"I. That species not generally distributed exist in waters on different
sides of the great watershed.
"II. That the distribution of the species is not governed by the outlet
of the rivers, streams having similar discharges (Holston and Kanawha,
Roanoke and Susquehanna) having less in common than others having
different outlets (Kanawha, or Susquehanna and James).
[Illustration: FIG. 187.--Butterfly-sculpin, _Melletes papilio_ Bean, a
fish of the rock-pools. St. Paul, Pribilof Islands.]
"In view of the first proposition, and the question of the origin of
species, the possibility of an original or subsequent mingling of the
fresh waters suggests itself as more probable than that of distinct
origin in the different basins."
=Questions Raised by Cope.=--Two questions in this connection are
raised by Prof. Cope. The first question is this: "Has any destruction
of the river faunæ taken place since the first elevation of the
Alleghanies, when the same species were thrown into waters flowing in
opposite directions?" Of such destruction by submergence or otherwise,
Prof. Cope finds no evidence. The second question is, "Has any means
of communication existed, at any time, but especially since the last
submergence, by which the transfer of species might occur?" Some
evidence of such transfer exists in the wide distribution of certain
species, especially those which seek the highest streamlets in the
mountains; but except to call attention to the cavernous character
of the Subcarboniferous and Devonian limestones, Prof. Cope has made
little attempt to account for it.
Prof. Cope finally concludes with this important generalization:
"It would appear, from the previous considerations, that the
distribution of fresh-water fishes is governed by laws similar to those
controlling terrestrial vertebrates and other animals, in spite of the
seemingly confined nature of their habitat."
=Views of Günther.=--Dr. Günther[74] has well summarized some of the
known facts in regard to the manner of dispersion of fishes:
"The ways in which the dispersal of fresh-water fishes has been
affected were various. They are probably all still in operation,
but most work so slowly and imperceptibly as to escape direct
observation; perhaps they will be more conspicuous after science and
scientific inquiry shall have reached a somewhat greater age. From the
great number of fresh-water forms which we see at this present day
acclimatized in, gradually acclimatizing themselves in, or periodically
or sporadically migrating into, the sea, we must conclude that under
certain circumstances salt water may cease to be a barrier at some
period of the existence of fresh-water species, and that many of them
have passed from one river through salt water into another. Secondly,
the headwaters of some of the grandest rivers, the mouths of which are
at opposite ends of the continents which they drain, are sometimes
distant from each other a few miles only. The intervening space may
have been easily bridged over for the passage of fishes by a slight
geological change affecting the level of the watershed or even by
temporary floods; and a communication of this kind, if existing for a
limited period only, would afford the ready means of an exchange of
a number of species previously peculiar to one or the other of these
river or lake systems. Some fishes provided with gill-openings so
narrow that the water moistening the gills cannot readily evaporate,
and endowed, besides, with an extraordinary degree of vitality, like
many Siluroids (_Chlarias_, _Callichthys_), eels, etc., are enabled to
wander for some distance over land, and may thus reach a water-course
leading them thousands of miles from their original home. Finally,
fishes or their ova may be accidentally carried by water-spouts, by
aquatic birds or insects, to considerable distances."
=Fresh-water Fishes of North America.=--We now recognize about six
hundred species[75] of fishes as found in the fresh waters of North
America, north of the Tropic of Cancer, these representing thirty-four
of the natural families. As to their habits, we can divide these
species rather roughly into the four categories proposed by Prof. Cope,
or, as we may call them,
(1) Lowland fishes; as the bowfin,[76] pirate-perch,[77] large-mouthed
black bass,[78] sunfishes, and some catfishes.
(2) Channel-fishes; as the channel catfish,[79] the mooneye,[80]
garpike,[81] buffalo-fishes,[82] and drum.[83]
(3) Upland fishes; as many of the darters, shiners, and suckers, and
the small-mouthed black bass.[84]
(4) Mountain-fishes; as the brook trout and many of the darters and
minnows.
To these we may add the more or less distinct classes of (5) lake
fishes, inhabiting only waters which are deep, clear, and cold, as
the various species of whitefish[85] and the Great Lake trout;[86]
(6) anadromous fishes, or those which run up from the sea to spawn in
fresh waters, as the salmon,[87] sturgeon,[88] shad,[89] and striped
bass;[90] (7) catadromous fishes, like the eel,[91] which pass down to
spawn in the sea; and (8) brackish-water fishes, which thrive best in
the debatable waters of the river-mouths, as most of the sticklebacks
and the killifishes.
As regards the range of species, we have every possible gradation
from those which seem to be confined to a single river, and are rare
even in their restricted habitat, to those which are in a measure
cosmopolitan,[92] ranging everywhere in suitable waters.
=Characters of Species.=--Still, again, we have all degrees of
constancy and inconstancy in what we regard as the characters of a
species. Those found only in a single river-basin are usually uniform
enough; but the species having a wide range usually vary much in
different localities. Such variations have at different times been
taken to be the indications of as many different species. Continued
explorations bring to light, from year to year, new species; but the
number of new forms now discovered each year is usually less than the
number of recognized species which are yearly proved to be untenable.
Four complete lists of the fresh-water fishes of the United States
(north of the Mexican boundary) have been published by the present
writer. That of Jordan and Copeland,[93] published in 1876, enumerates
670 species. That of Jordan[94] in 1878 contains 665 species, and that
of Jordan and Gilbert[95] in 1883, 587 species. That of Jordan and
Evermann[96] in 1898 contains 585 species, although upwards of 130 new
species were detected in the twenty-two years which elapsed between
the first and the last list. Additional specimens from intervening
localities are often found to form connecting links among the nominal
species, and thus several supposed species become in time merged
in one. Thus the common channel catfish[97] of our rivers has been
described as a new species not less than twenty-five times, on account
of differences real or imaginary, but comparatively trifling in value.
Where species can readily migrate, their uniformity is preserved;
but whenever a form becomes localized its representatives assume some
characters not shared by the species as a whole. When we can trace,
as we often can, the disappearance by degrees of these characters,
such forms no longer represent to us distinct species. In cases where
the connecting forms are extinct, or at least not represented in
collections, each form which is apparently different must be regarded
as a distinct species.
The variations in any type become, in general, more marked as we
approach the tropics. The genera are represented, on the whole, by
more species there, and it would appear that the processes of specific
change go on more rapidly under the easier conditions of life in the
Torrid Zone.
We recognize now in North America twenty-five distinct species of
fresh-water catfishes,[98] although nearly a hundred (93) nominal
species of these fishes have been from time to time described. But
these twenty-five species are among themselves very closely related,
and all of them are subject to a variety of minor changes. It
requires no strong effort of the imagination to see in them all the
modified descendants of some one species of catfish, not unlike our
common "bullhead,"[99] an immigrant probably from Asia, and which
has now adjusted itself to its surroundings in each of our myriad of
catfish-breeding streams.
=Meaning of Species.=--The word "species," then, is simply a term of
convenience, including such members of a group similar to each other as
are tangibly different from others, and are not known to be connected
with these by intermediate forms. Such connecting links we may suppose
to have existed in all cases. We are only sure that they do not now
exist in our collections, so far as these have been carefully studied.
When two or more species of any genus now inhabit the same
waters, they are usually species whose differentiation is of long
standing,--species, therefore, which can be readily distinguished
from one another. When, on the other hand, we have "representative
species,"--closely related forms, neither of which is found within the
geographical range of the other,--we can with some confidence look
for intermediate forms where the territory occupied by the one bounds
that inhabited by the other. In very many such cases the intermediate
forms have been found; and such forms are considered as subspecies of
one species, the one being regarded as the parent stock, the other
as an offshoot due to the influences of different environment. Then,
besides these "species" and "subspecies," groups more or less readily
recognizable, there are varieties and variations of every grade, often
too ill-defined to receive any sort of name, but still not without
significance to the student of the origin of species. Comparing a
dozen fresh specimens of almost any kind of fish from any body of
water with an equal number from somewhere else, one will rarely fail
to find some sort of differences,--in size, in form, in color. These
differences are obviously the reflex of differences in the environment,
and the collector of fishes seldom fails to recognize them as such;
often it is not difficult to refer the effect to the conditions. Thus
fishes from grassy bottoms are darker than those taken from over
sand, and those from a bottom of muck are darker still, the shade of
color being, in some way not well understood, dependent on the color
of the surroundings. Fishes in large bodies of water reach a larger
size than the same species in smaller streams or ponds. Fishes from
foul or sediment-laden waters are paler in color and slenderer in form
than those from waters which are clear and pure. Again, it is often
true that specimens from northern waters are less slender in body
than those from farther south; and so on. Other things being equal,
the more remote the localities from each other, the greater are these
differences.
[Illustration: FIG. 188.--_Scartichthys enosimæ_ Jordan and Snyder, a
fish of the rock-pools of the sacred island of Enoshima, Japan. Family
_Blenniidæ_.]
In our fresh-water fishes each species on an average has been described
as new from three to four times, on account of minor variations, real
or supposed. In Europe, where the fishes have been studied longer and
by more different men, upwards of six or eight nominal species have
been described for each one that is now considered distinct.
=Special Creation Impossible.=--It is evident, from these and other
facts, that the idea of a separate creation for each species of fishes
in each river-basin, as entertained by Agassiz, is wholly incompatible
with our present knowledge of the specific distinctions or of the
geographical distribution of fishes. This is an unbroken gradation in
the variations from the least to the greatest,--from the peculiarities
of the individual, through local varieties, geographical subspecies,
species, sub-genera, genera, families, super-families, and so on, until
all fish-like vertebrates are included in a single bond of union.
=Origin of American Species of Fishes.=--It is, however, evident that
not all American types of fishes had their origin in America, or even
first assumed in America their present forms. Some of these are perhaps
immigrants from northern Asia, where they still have their nearest
relatives. Still others are evidently modified importations from the
sea; and of these some are very recent immigrants, land-locked species
which have changed very little from the parent stock.
The problems of analogous variation or parallelism without homology
are very often met with among fishes. In shallow, swift brooks in all
lands there are found small fishes which hug the bottom--large-finned,
swift of movement, with speckled coloration, and with the air-bladder
reduced in size. In the eastern United States these fishes are darters,
dwarf perches; in northern India they are catfishes; in Japan, gobies
or loaches; in Canada, sculpins; in South America, characins. Members
of various groups may be modified to meet the same conditions of
life. Being modified to look alike, the thought of mutual affinity
is naturally suggested, but in such cases the likeness is chiefly
external. The internal organs show little trace of such modifications.
The inside of an animal tells what it really is, the outside where
it has been. In other words, it is the external characters which are
most readily affected by the environment. Throughout all groups of
animals and plants, there are large branches similarly affected by
peculiarities of conditions.
This is the basis of the law of "Adaptive Radiation." Prof. H. F.
Osborn thus states this law:
"It is a well-known principle of zoological evolution that an isolated
region, if large and sufficiently varied in its topography, soil,
climate, and vegetation, will give rise to a diversified fauna
according to the law of adaptive radiation from primitive and central
types. Branches will spring off in all directions to take advantage of
every possible opportunity of securing food. The modifications which
animals undergo in this adaptive radiation are largely of mechanical
nature; they are limited in number and kind by hereditary stirp or
germinal influences, and thus result in the independent evolution of
similar types in widely separated regions under the law of parallelism
or homoplasy."
FOOTNOTES:
[63] This chapter and the next are in substance reprinted from an essay
published by the present writer in a volume called Science Sketches. A.
C. McClurg & Co., Chicago.
[64] _Salvelinus fontinalis_ Mitchill.
[65] _Semotilus atromaculatus_ Mitchill.
[66] _Notropis cornutus_ Rafinesque.
[67] _Catostomus commersoni_ (Lacépède).
[68] _Ameiurus melas_ Rafinesque.
[69] _Eupomotis gibbosus_ Linnæus.
[70] _Etheostoma flabellare_ Rafinesque.
[71] _Rhinichthys atronasus_ Mitchill.
[72] On Fishes from Tennessee River, Alabama. American Journal of
Science and Arts, xvii., 2d series, 1854, p. 26.
[73] On the Distribution of Fresh-water Fishes in the Alleghany Region
of Southwestern Virginia. Journ. Acad. Nat. Sci., Phila., 1868, pp.
207-247.
[74] Introduction to the Study of Fishes, 1880, p. 211.
[75] The table below shows approximately the composition of the
fresh-water fish fauna of Europe, as compared with that of North
America north of the Tropic of Cancer.
Families. Europe. N. America.
Lamprey _Petromyzonidæ_ 3 species. 8 species.
Paddle-fish _Polyodontidæ_ -- " 1 "
Sturgeon _Acipenseridæ_ 10 " 6 "
Garpike _Lepisosteidæ_ -- " 3 "
Bowfin _Amiidæ_ -- " 1 "
Mooneye _Hiodontidæ_ -- " 3 "
Herring _Clupeidæ_ 2 " 5 "
Gizzard-shad _Dorosomidæ_ -- " 1 "
Salmon _Salmonidæ_ 12 " 28 "
Characin _Characinidæ_ -- " 1 "
Carp _Cyprinidæ_ 61 " 230 "
Loach _Cobiridæ_ 3 " -- "
Sucker _Catostomidæ_ -- " 51 "
Catfish _Siluridæ_ 1 " 25 "
Trout-perch _Percopsidæ_ -- " 2 "
Blindfish _Amblyopsidæ_ -- " 6 "
Killifish _Cyprinodontidæ_ 3 " 52 "
Mud-minnow _Umbridæ_ 1 " 2 "
Pike _Esocidæ_ 1 " 5 "
Alaska blackfish _Dalliidæ_ -- " 1 "
Eel _Anguillidæ_ 2 " 1 "
Stickleback _Gasterosteidæ_ 3 " 7 "
Silverside _Atherinidæ_ 2 " 2 "
Pirate perch _Aphredoderidæ_ -- " 1 "
Elassoma _Elassomidæ_ -- " 2 "
Sunfish _Centrarchidæ_ -- " 37 "
Perch _Percidæ_ 11 " 72 "
Bass _Serranidæ_ 1 " 4 "
Drum _Sciænidæ_ -- " 1 "
Surf-fish _Embiotocidæ_ -- " 1 "
Cichlid _Cichlidæ_ -- " 2 "
Goby _Gobiidæ_ 2 " 6 "
Sculpin _Cottidæ_ 2 " 21 "
Blenny _Blenniidæ_ 3 " -- "
Cod _Gadidæ_ 1 " 1 "
Flounder _Pleuronectidæ_ 1 " -- "
Sole _Soleidæ_ 1 " 1 "
Total: Europe, 21 families; 126 species. North America, 34 families;
590 species. A few new species have been added since this enumeration
was made.
According to Dr. Günther (Guide to the Study of Fishes, p. 243), the
total number of species now known from the temperate regions of Asia
and Europe is about 360. The fauna of India, south of the Himalayas,
is much more extensive, numbering 625 species. This latter fauna bears
little resemblance to that of North America, being wholly tropical in
its character.
[76] _Amia calva_ Linnæus.
[77] _Aphredoderus sayanus_ Gilliams.
[78] _Micropterus salmoides_ Lacépède.
[79] _Ictalurus punctatus_ Rafinesque.
[80] _Hiodon tergisus_ Le Sueur.
[81] _Lepisosteus osseus_ Linnæus.
[82] _Ictiobus bubalus_, _cyprinella_, etc.
[83] _Aplodinotus grunniens_ Rafinesque.
[84] _Micropterus dolomieu_ Lacépède.
[85] _Coregonus clupeiformis_, _Argyrosomus artedi_, etc.
[86] _Cristivomer namaycush_ Walbaum.
[87] _Salmo salar_ Linnæus.
[88] _Acipenser sturio_ and other species.
[89] _Alosa sapidissima_ Wilson.
[90] _Roccus lineatus_ Bloch.
[91] _Anguilla chrysypa_ Raf.
[92] Thus the chub-sucker (_Erimyzon sucetta_) in some of its varieties
ranges everywhere from Maine to Dakota, Florida, and Texas; while a
number of other species are scarcely less widely distributed.
[93] Check List of the Fishes of the Fresh Waters of North America,
by David S. Jordan and Herbert E. Copeland. Bulletin of the Buffalo
Society of Natural History, 1876, pp. 133-164.
[94] A Catalogue of the Fishes of the Fresh Waters of North America.
Bulletin of the United States Geological Survey, 1878, pp. 407-442.
[95] A Catalogue of the Fishes Known to Inhabit the Waters of
North America North of the Tropic of Cancer. Annual Report of the
Commissioner of Fish and Fisheries for 1884 and 1885.
[96] Check List of the Fishes of North and Middle America. Report of
the U. S. Commissioner of Fisheries for 1895.
[97] _Ictalurus punctatus_ Rafinesque.
[98] _Siluridæ._
[99] _Ameiurus nebulosus._