GENERA ATHYRIS, ETC. 259 



*' confusion that has arisen through conflicting views on the question of 

 " nomenclature, and, agreeing with Mr. Billings in the conclusion he 

 "had come to, stated that this communication was valuable, insomuch as 

 " it cleared up a question that had been rendered obscure."* 



Thus fortified in the outset, Mr. B. starts off upon his argument, which, 

 could such a thing ever be suspected of this author, would have very much 

 the appearance and arrangement of a case of special pleadings. He closes 

 his article by a citation from a former one, recommending Mr, Hall to 

 treat the subject " in a clear and unsophisticated manner." 



We appreciate this appeal of Mr. Billings, and sympathise in his 

 dilemma, when, after appearing in several articles on this subject (in none 

 of which has he added anything to our knowledge of the matter), he finds 

 himself unable to present an ^^ ujisophisticated^^ view of the case, he 

 appeals to his opponent to come to his aid. We would endeavor to oblige 

 the courteous writer, but being just now very much engaged in the study 

 of the structure and relations of these fossils, we have less time to discuss 

 questions of nomenclature which have been for some time settled in the 

 minds of most naturalists. 



There are, however, one or two points which it may be well to take 

 notice of here ; and however a writer may choose to disguise the facts, 

 they must necessarily become known to every investigator of fossils. The 

 generic name Athyris was given by Prof. M'CoY in 1844 (Carboniferous 

 Fossils of Ireland, p. 146) ; and under it are cited in the following order, 

 A. concentrica, A. decussata, A. depressa, A. expansa, A. Jimbriata, A. 

 glabristria, A. globularis, A. hispida, A. planosulcata, A. squamosa^ and 

 A. (?) triloba. These, with the exception of the last one, are retained by 

 Mr. Davidson, either as species or synonyms under the Genus Athyris. 



In 1847, D'Orbigny, objecting to the term Athyris on account 

 of its implying a zoological contradiction, proposed the name Spirigera; 

 making it precisely equivalent to Athyris, and citing the same species 

 under it, including also others, but making S. concentrica the typical 

 species. Let us cite here a rule, which is likewise cited by Mr. Billings: 



§ " When two authors define and name the same genus, both making it exactly of 

 " the same extent, the latter name should be cancelled in toto, and not retained in 

 " a modified sense. ^' 



Mr. Billings gives an ideal figure of M'Coy — or at least, if not ideal, 

 it is given without a name in the " Carboniferous Fossils of Ireland," page 

 128 (fig. 19) — and speaks of it as the " typical figure. He copies " Spiri- 

 gera concentrica (von Buch) from Davidson's Monograph of British 

 Devonian Brachiopoda, "a little restored, with the aperture in the beak 



* I trust the gentlemen here referred to will not take offence at being thus cited by mo : 

 this is neither my intent or animus. Whgther or not it may have been in good taste to 

 associate their names in this manner with the article in the Am. Journal of Science, I 

 do not undertake to decide. Every one can appreciate the value of opinions expressed under 

 such circumstances, whore the parties themselves have made no investigation of the 

 matter, and accept without criticism the sfeatoments of a writer or speaker. 



