NOMENCLATURE.
“I do not think more credit is due to a man for defining a species,
than to a carpenter for making a box.”
CHARLES DARWIN, _Life and Letters_, Vol. I., p. 371.
Any attempt to discuss at length the difficult and thorny question
of nomenclature would be entirely out of place in an elementary book
on fossil plants, but there are certain important points to which it
may be well to draw attention. When a student enters the field of
independent research, he is usually but imperfectly acquainted with the
principles of nomenclature which should be followed in palaeontological
work. After losing himself in a maze of endless synonyms and confused
terminology, he recognises the desirability of adopting some definite
and consistent plan in his method of naming genera and species. It is
extremely probable that whatever system is made use of, it will be
called in question by some critics as not being in strict conformity
with accepted rules. The opportunities for criticism in matters
relating to nomenclature are particularly numerous, and the critic who
may be but imperfectly familiar with the subject-matter of a scientific
work is not slow to avail himself of some supposed eccentricity on the
part of the author in the manner of terminology. The true value of work
may be obscured by laying too much emphasis on the imperfections of a
somewhat heterodox nomenclature. On the other hand good systematic work
is often seriously spoilt by a want of attention to generally accepted
rules in naming and defining species. It is essential that those who
take up systematic research should pay attention to the necessary
though secondary question of technical description.
[Sidenote: RULES FOR NOMENCLATURE.]
In inventing a new generic or specific name, it is well to adhere to
some definite plan as regards the form or termination of the words
used. To deal with this subject in detail, or to recapitulate a
series of rules as to the best method of constructing names whether
descriptive or personal, would take us beyond the limits of a single
chapter. The student should refer for guidance to such recognised rules
as those drawn up by the late Mr Strickland and others at the instance
of the British Association[158].
It is not infrequently the case that the same generic name has been
applied to a fossil and to a recent species. Such a double use of the
same term should always be avoided as likely to lead to confusion, and
as tending to admit a divorce between botany and palaeobotany.
In the course of describing a collection of fossil species, various
problems are bound to present themselves as regards the best method
of dealing with certain generic or specific names. A few general
suggestions may prove of use to those who are likely to be confronted
with the intricacies of scientific and pseudoscientific terminology.
In writing the name of a species, it is important to append the name,
often in an abbreviated form, of the author who first proposed the
accepted specific designation. _Stigmaria ficoides_ Brongn. written
in this form records the fact that Brongniart was the author of the
specific name _ficoides_. It means, moreover, that Brongniart not
only suggested the name, but that he was the first to give either a
figure or a diagnosis of this particular fossil. It is frequently
the case that a specific name is proposed for a new species, without
either figures or description; such a name is usually regarded as a
_nomen nudum_, and must yield priority to the name which was first
accompanied by some description or illustration sufficiently accurate
to afford a means of recognition. A practice which may be recommended
on the score of convenience is to write the name of the author of a
species in brackets if he was not the first to use the generic as well
as the specific name. _Onychiopsis Mantelli_ (Brongn.) tells us that
Brongniart founded the species, but made use of some other generic
name than that which is now accepted. This leads us to another point
of some importance. Brongniart described this characteristic Wealden
fern under the name _Sphenopteris Mantelli_; _Sphenopteris_ being one
of those extremely useful provisional generic terms which are used
in cases where we have no satisfactory proof of precise botanical
affinity. _Sphenopteris_ stands for fern fronds having a certain habit,
form of segment and venation, and in this wide sense it necessarily
includes representatives of various divisions and genera of Filices. If
an example of a sphenopteroid frond is discovered with sori or spores
sufficiently well preserved to enable us to determine its botanical
position within narrower limits, we may with advantage employ another
genus in place of the purely artificial form-genus which was originally
chosen as a consequence of imperfect knowledge. Fronds of this Wealden
fern have recently been found with well defined fertile segments
having a form apparently identical with that which characterises the
polypodiaceous genus _Onychium_. For this reason the name _Onychiopsis_
has been adopted. It is safer and more convenient to use a name which
differs in its termination from that of the recent plant with which
we believe the fossil to be closely related. A common custom is to
slightly alter the recent name by adding the termination _-opsis_ or
_-ites_. There are several other provisional generic terms that are
often used in Fossil Botany, and which might be advantageously chosen
in many cases where the misleading resemblance of external form has
often given rise to the use of a name implying affinities which cannot
be satisfactorily demonstrated.
It was the custom of some of the earliest writers, in spite of their
habit of using the names of recent Flowering plants for extinct
Palaeozoic species of Vascular Cryptogams, to adopt also general and
comprehensive terms. We find such a name as _Lithoxylon_ employed by
Lhwyd[159] in 1699 as a convenient designation for fossil wood.
[Sidenote: THE RULE OF PRIORITY.]
One of the most important and frequently disputed questions associated
with the naming of species is that of priority. No name given to a
plant in pre-Linnaean days need be considered, as our present system
of nomenclature dates from the institution of the binominal system
by Linnaeus. As a general rule, which it is advisable to follow, the
specific name which was first given to a plant, if accompanied by a
figure or diagnosis, should take priority over a name of later date.
If _A_ in 1850 describes a species under a certain name, and in 1860
_B_ proposes a new name for the same species, either in ignorance
of the older name or from disapproval of _A_’s choice of a specific
term, the later name should not be allowed to supersede _A_’s original
designation. Such a rule is not only just to the original author, but
is one which, if generally observed, would lead to less confusion and
would diminish unnecessary multiplication of specific names. Some
writers would have us conform in all cases to this rule of priority,
which they consistently adhere to apart from all considerations of
convenience or long-established custom. There are, however, cogent
reasons for maintaining a certain amount of freedom. While accepting
priority as a good rule in most cases, it is unwise to allow ourselves
to be too servile in our conformity to a principle which was framed in
the interests of convenience, if the strict application of the rule
clearly makes for confusion and inconvenience. A name may have been
in use for say eighty years, and has become perfectly familiar as
the recognised designation of a particular fossil; it is discovered,
however, that an older name was proposed for the same species ninety
years ago, and therefore according to the priority rule, we must
accustom ourselves to a new name in place of one which is thoroughly
established by long usage. From a scientific point of view, the ideal
of nomenclature is to be plain and intelligible. To prefer priority to
established usage entails obscurity and confusion. If priority is to
be the rule which we must invariably obey in the shadowy hope that by
such means finality in nomenclature[160] may be reached, it becomes
necessary for the student to devote no inconsiderable portion of
his time to antiquarian research, with a view to discover whether a
particular name may be stamped with the hallmark of ‘the very first.’
While admitting the advisability of retaining as a general principle
the original generic or specific name, the extreme subservience to
‘the priority craze’ without regard to convenience, would seem to lead
irresistibly to the view that “botanists who waste their time over
priority are like boys who, when sent on an errand, spend their time in
playing by the roadside[161].”
[Sidenote: TERMINOLOGY AND CONVENIENCE.]
There is another point which cannot be satisfactorily settled in all
cases by a rigid adherence to an arbitrary rule. How far should we
regard a generic name in the sense of a mere mark or sign to denote a
particular plant, or to what extent may we accept the literal meaning
of the generic term as an index of the affinity or character of the
plant? If we consider the etymology of many generic names, we soon find
that they are entirely inappropriate as aids in recognizing the true
taxonomic position of the plants to which they are applied. The generic
name _Calamites_ was first suggested by the supposed resemblance of
this Palaeozoic plant to recent reeds. If considered etymologically,
it is merely a record of a past mistake, but it would be absurd to
discard such a well-known name on the grounds that the genus is a
Vascular Cryptogam and far removed from reeds. On the other hand,
there often arise cases which present a real difficulty. The following
example conveniently illustrates two distinct points of view as regards
generic nomenclature. In 1875 Saporta described and figured a fragment
of a fossil plant from the Jurassic beds of France as _Cycadorachis
armata_[162]; the name being chosen in the belief that the specimen
was part of a cycadean petiole, and there were good grounds for such
a view. A few years ago Mr Rufford discovered more perfect specimens,
in the Wealden rocks of Sussex, clearly belonging to Saporta’s genus,
and these afforded definite evidence that Saporta had been deceived by
the imperfection of the specimens as to their true botanical position.
Owing to the obviously misleading name first given to this plant, I
ventured to substitute _Withamia_[163] for _Cycadorachis_, and chose
such a term in preference to one denoting affinity, on account of the
difficulty of placing the plant in a definite class or family. On
the other hand, it has been objected that the original name, despite
its meaningless meaning—if the expression may be used—should be
retained. A friendly critic[164], in writing of the proposed change
of _Cycadorachis_, urges the importance of adhering to the name which
was first applied to a genus. The same author pertinently remarks that
we can no more dispense with a nomenclature than we can dispense with
language. We may extend the comparison and point out that in language,
as in scientific nomenclature, conciseness, clearness and convenience
should be kept in view as guiding principles.
The student must judge for himself what course to follow in each
case. While adhering as far as possible to a consistent plan, he must
take care that he does not allow his own judgment to be completely
over-ridden by a blind obedience to fixed rules, which if pressed too
far may defeat their own ends.
=PART II. SYSTEMATIC.=