GENUS ATHYRIS. 265 



whether they may correspond with the spires in the ^^ typical figure'''' of 

 Athyris cited by him, I am not prepared to say, nor can I assert that they 

 correspond with the similar appendages in M. tumida. Of the other species, 

 A, TnaiUy I have had in my collection, for many years, specimens from the 

 locality in Canada cited by Mr. Billings, and also from Ohio; but I 

 have always regarded it as a true Spirifei\ and until it shall be proved 

 destitute of area,* and with internal appendages corresponding to Athyris, 

 I shall prefer to know it as a Spirifer. Even admitting all that Mr. Bil- 

 lings has claimed in regard to Athyris, it does not appear that he is 

 prepared to give us much information in regard to the extent and limits of 

 the genus about which he has written so much. 



Note. — Since it appears that zoological nomenclature and argument, 

 and not structural characters are to be relied upon for the establishment 

 of the points in dispute, therefore ; In order that the student of Palajon- 

 tology may have the benefit.. of Mr. Davidson's opinions upon the question 

 of nomenclature, regarding Athyris and Spirigera, I have translated from 

 the French edition of his Introduction to the Study of Brachiopoda(1856), 

 the following observations. It is easy to understand how certain authors, 

 following the views of Mr. Davidson published in 1853, should have 

 adopted the names of Athyris and Spirigera : 



" In 1853, I was very much perplexed in regard to the name jlthyris, proposed by 

 Prof, M'CoY for certain species which ill accorded either with the etymology of that 

 name, or with the diagnosis given briefly, and without detail, at the outset; that is to 

 S2ij, nearly orbicular, small; without area or cardinal line; spiral appendages very 

 large, occupying the greater portion of the interior of the shell. The author cites 

 some examples, among which are shells evidently perforate, such as the T. concen- 

 trica (deBuch), and others which do not appear to be so; and furthermore some 

 belonging to the genus Spirifera of Sowerby. It is true that the Professor alleged 

 in support of his theory, that his type, cited above, was, when in a state of perfect 

 preservation, imperforate, and that he had given to this section a name expressive 

 of a real characteristic. In 1859, M. D'Orbigny opposed the appellation given by 

 M'CoY, on the ground that it was in complete contradiction to the zoological 

 characteristics.* He proposed to substitute in its place the name Spirigera; and 

 chose, moreover, as the type, the T. concentrica of Baron DeBuch. About ihe year 

 1835 or 1836, Prof. King, having received from the Eifel a specimen labelled T. 

 concentrica, but which was in reality the T. scalprum, described it by mistake as the 

 species of the Baron, ' having the hinge-plates attached to a process resembling a 

 shoe-horn.'^ Imbued with this idea, and justly remarking certain important differen- 

 ces in the Permian species (T. pectinifera) , he proposed to distinguish this latter by 

 a particular generic appellation. He chose, for this purpose, the name Cleiothyris, of 

 Phillips ;t which, however, had not been used by its originator precisely in tbis 

 sense. The fact is, that the true T. concentrica and the true T. pectinifera, although 

 distinct species, have an organization essentially similar and belong to the same 

 group. But, on the other hand, the Athyris concentrica of Prof. King possesses the 

 characteristics of another section (Merista, Suess), of which the T. tumida (Dalm.) 

 or the T. herculea (of Barrande) may serve as types. As tbough to a'^d to the con- 

 fusion already existing in the nomenclature pertaining to this genus, we learn from 



* I might remark that although described as without area, the artist has taken the 

 liberty of indicating something of the kind in the figure of the specimen. 



[Assem. No. 23y.j U 



