It is true that common consent fixes the date of the beginning of nomenclature at 1758. But to this there are many exceptions. Some writers date genera from the first recognition of a collective idea under a single name. Others follow even species back through the occasional accidental binomials. Most British writers have chosen the final and completed edition of the Systema Naturæ, the last work of Linnæus, in 1766, in preference to the earlier volume. But all things considered, justice and convenience alike seem best served by the use of the edition of 1758.
Synonymy and Priority.—Synonymy is the record of the names applied at different times to the same group or species. With characteristic pungency Dr. Coues defines synonymy as "a burden and a disgrace to science." It has been found that the only way to prevent utter confusion is to use for each genus or species the first name applied to it and no other. The first name, once properly given, is sacred because it is the right name. All other later names whatever their appropriateness are wrong names. In science, of necessity, a name is a name without any necessary signification. For this reason and for the further avoidance of confusion, it remains as it was originally spelled by the author, obvious misprints aside, regardless of all possible errors in classical form or meaning. The names in use are properly written in Latin or in Latinized Greek, the Greek forms being usually preferred as generic names, the Latin adjectives for names of species. Many species are named in honor of individuals, these names being usually given the termination of the Latin genitive, as Sebastodes gillii, Liparis agassizi. In recent custom all specific names are written with the small initial; all generic names with the capital.
One class of exceptions must be made to the law of priority. No generic name can be used twice among animals, and no specific name twice in the same genus. Thus the name Diabasis has to be set aside in favor of the next name Hæmulon, because Diabasis was earlier used for a genus of beetles. The specific name Pristipoma humile is abandoned, because there was already a humile in the genus Pristipoma.
The Conception of Genus.—In the system of Linnæus, a genus corresponds roughly to the modern conception of a family. Most of the primitive genera contained a great variety of forms, as well as usually some species belonging to other groups disassociated from their real relationships.
As greater numbers of species have become known the earlier genera have undergone subdivision until in the modern systems almost any structural character not subject to intergradation and capable of exact definition is held to distinguish a genus. As the views of these characters are undergoing constant change, and as different writers look upon them from different points of view, or with different ideas of convenience, we have constant changes in the boundaries of genera. This brings constant changes in the scientific names, although the same specific name should be used whatever the generic name to which it may be attached. We may illustrate these changes and the burden of synonymy as well by a concrete example.
The Trunkfishes.—The horned trunkfish, or cuckold, of the West Indies was first recorded by Lister in 1686, in the descriptive phrase above quoted. Artedi, in 1738, recognized that it belonged with other trunkfishes in a group he called Ostracion. This, to be strictly classic, he should have written Ostracium, but he preferred a partly Greek form to the Latin one. In the Nagg's Head Inn in London, Artedi saw a trunkfish he thought different, having two spines under the tail, while Lister's figure seemed to show one spine above. This Nagg's Head specimen Artedi called "Ostracion triangulatus duobus aculeis in fronte et totidem in imo ventre subcaudalesque binis."
Next came Linnæus, 1758, who named Lister's figure and the species it represented, Ostracion tricornis, which should in strictness have been Ostracion tricorne, as ὀστρακίον, a little box, is a neuter diminutive. The Nagg's Head fish he named Ostracion quadricornis. The right name now is Ostracion tricornis, because the name tricornis stands first on the page in Linnæus' work, but Ostracion quadricornis has been more often used by subsequent authors because it is more truthful as a descriptive phrase. In 1798, Lacépède changed the name of Lister's fish to Ostracion listeri, a needless alteration which could only make confusion.
Fig. 240.—Horned Trunkfish, Ostracion cornutum Linnæus. East Indies. (After Bleeker.)
In 1818, Dr. Samuel Latham Mitchill, receiving a specimen from below New Orleans, thought it different from tricornis and quadricornis and called it Ostracion sexcornutus; Dr. Holard, of Paris, in 1857, named a specimen Ostracion maculatus, and at about the same time Bleeker named two others from Africa which seem to be the same thing, Ostracion guineensis and Ostracion gronovii. Lastly, Poey calls a specimen from Cuba Acanthostracion polygonius, thinking it different from all the rest, which it may be, although my own judgment is otherwise. This brings up the question of the generic name. Among trunkfishes there are four-angled and three-angled kinds, and of each form there are species with and without horns and spines. The original Ostracion of Linnæus we may interpret as being Ostracion cubicus of the coasts of Asia, a species similar to the Ostracion rhinorhynchus. This species, cubicus, we call the type species of the genus, as the Nagg's Head specimen of Artedi was the type specimen of the species quadricornus, and the one that was used for Lister's figure the type specimen of tricornis.