CHAPTER VI.
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.
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.
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].”
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.