CONTRIBUTIONS TO PAL2E0NT0L0GY. 305 



proposed to substitute in its place the name Spirigeea, and chose, moreover, 

 as the type the T. concentrica of Baron De Buch. About the year 1835 or 

 1836, Prof. King, having received from the Eifel a specimen labeled T. con- 

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

 the species of the Barou, ' having the hinge-plates attached to a process resem- 

 bling a shoe-Jiorn.^ * Imbued with this idea, and justly remarking certain 

 important differences in the Permian species {T. pectinifera), he proposed to 

 distinguish this latter by a particular generic appellation. He chose for this 

 purpose the name Cleiothyeis of Phillips, f which, however, had not been 

 used by its originator precisely in this sense. The fact is that the true T. 

 concentrica and the true T. yectinifera, 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 (Mepjsta of Suess), of which the T. tumida, Dalm., or the T. 

 herculea of Baeeande may serve as types. As though to add to the confusion 

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

 recent publication t of Prof M'Cot that he has added to the diagnosis of Athteis 

 a trifling but important modification, which is ' that there exists a strong median 

 septum in the rostral portion of the entering valve ; the dental lamelloe are 

 moderate ; there is no foramen. Example, A. tumida, Dai.m.' This diagnosis 

 in no way befits the T. concentrica ; but, on the contrary, it accords peifectly 

 with the condition observable in the group characterized by the T. tumida and 

 herculea. It is evident from all this that nearly all authors have united two 

 distinct groups of shells under the name of Athteis or that of Spirigeea. 

 In order to put an end to this confusion, and to avoid at the same time the 

 necessity of new names, I proposed in the English edition of my British Fossil 

 Bracldopoda, 1853, to preserve the name Athteis for the group characterized 

 by the T. tumida, herculea, scalprum, etc., and the name Spieigeea of D'Oebignt 

 for such shells as the T. concentrica, lamellosa, roissyi, pectinifera, etc., thereby 

 avoiding, at least in some degree, the palpable contradiction of the name 

 employed by Prof. M'Coy, the name Spieigeea being evidently preferable to 

 that of Athteis. But this compromise has been criticised by many naturalists, 

 who insisted on the fact of the term Athteis having been origiuuHy aud posi- 

 tively applied by its originator to the T. concentrica, and also on the improj)riety 

 of the other appellation to designate such shells as the T. tumida, herculea, etc. 

 M. Suess informs us§ that, in 1851, he proposed the name Merista|| for the 

 group comprising these latter shells. I therefore abandon the proposition 

 I made in 1853, and retain indiflerently Athfeis of M'Cot or Spieigeea 



*Ann. and Mag. of Nat. Hist., Vol. xviii, p. 86, 1846. In this memoir Prof. King has admi- 

 rably described this remarkable process. 



"^ jl Monograph of the English Permian jPossiZs (Pal. Soc), p. 137, 1843. Prof. Phillips 

 proposed to substitute the name Cleiothyeis for Atrtpa of Dalman, but he has not made use 

 of it in this work. Fig. and Besc. of the Pal. Fos. in the Cambridge Museum, p. 196, 1852. 



t British Paleozoic Fossils in the Cambridge Museum, p. 196, 1852. 



§ Neues Jahrbuch, p. 62, January 1864. 



II Jahrb. d.K. Geol. Reichsanstalt, ii, iv, 150, 1851; mentioned also in Leonhard's Neues Jahr- 

 buch, p. 127, 1854. 



Cab. Nat. 39 



