122 PALjEONTOLOGY OF NEW YORK. 



not the Orbicula Norvegica of Lamarck * the Lamarckian species having proven 

 identical witli the Patella anomala of Mcller.j This latter species, however, is a 

 Crania ; and as the 0. Norvegica, Lamarck, was taken as the type-species of 

 Cuvier's genus Orbicula, the genus Orbicula, in its Cuvierian sense, becomes 

 a synonym for Crania. This fact of synonymy was pointed out by Dr. J. E. 

 Grav, as long ago as 182o,| but the genus Orbicula had become so thoroughly 

 confounded by authors with Disgina that, to avoid a disturbance of nomenclature, 

 the name was retained by Mr. Davidson§ and Professor Hall,|| as late as 1852, 

 for the DisciNA of authors, not of Lamarck. 



Li 1854, Mr. Davidson^ considered the Discina ostraoides, Lamarck, as iden- 

 tical with D. lamdlosa, Broderip, 1833,** and therefore, in the absence of a 

 description of D. ostraoides, assumed the latter as the tyj^e-species. This assump- 

 tion must now be regarded as inadmissible, and was abandoned by Mr. Davidson 

 in his "General Summary" (1884) and "Monograph of Recent Brachiopoda" 

 (1888).ff In accordance with Dall's observations, we are compelled to accept Dis- 

 cina striata, Schumacher {Crania striata, Schumacher, Essai d'un nouveau systeme 

 des habitudes des Vers Testacrs, p. 102, pi. xx, figs. 1 a-f, 1817, == Orbicula 

 Norvegica, ^owerhy, 1822, not Lamarck, \%'d\, = Discina ostrceoides, Lamarck, 

 ISl'.i), as the typical species of the genus. This species is not to be confounded 

 with the Discina striata, Sowerby,|:]: which is a Silurian (Ludlow) form, while 

 Schumacher's species, the designation of which antedates that of Sowerby, is 

 recent and of West African habitat. 



The diagnosis of the genus Discina, as derived from the species D. striata, 

 Schumacher, is given by Dall in the following terms: 



" Sub-genus Discina (Lam.), Dall. Shell of rather solid texture, with a con- 



* Sy.st. Nat, p. 140. 1801 ; and Hist. Animaux sans vei-tfeb., Ed. I, vol. vi, p. 242. 1819; Ed. 11, vol. 

 vii, p. 316. 1836. 



t Zoologiaj DaniciE Prodi-omus, p. 237. 177G. 

 I Annals of Philosophy, Now Sorio.s, vol. x. p. 244. 

 § Tertiary Brachiojioila. 

 1 Palajontology N. Y., vol.' ii. 

 *i] Introil. Brit. Foss. Brach. 

 ** Proc. Zool. Soc, vol. i, pp. 124, 125. 



tt Trans. Linnean Society, Second Series, Zoolog-y, vol. iv, pt. 3. 

 tt Sil. Sj'st., 111. V, fig-. 21. 1839, and Davidson, Silur. Brach., p. 07, pi. vi. li^'s. 1-4. 



