40 BULLETIN OF THE 



Orbicula striata Sowerby,** Thes. Conch., I, p. 366, pi. Ixxiii, fig. 9, 1847. 



— Forbes and Hanley, Brit. Moll., II, p. 368, 1853. — Davidson, An. 



Mag. Nat. Hist., IX, p. 376, 1852. Habitat 1 

 Orbicula Evansii Davidson, P. Z. S., 1852, p. 81, No. 12, pi. xiv, figs. 32 - 34. 



An. Mag. Nat. Hist, IX, p. 376, 1852. — Suess, Wolms., I, p. 44 (226), 



1859. Hab. Bodegas, Cal., in error. 

 Orbicula norvegica Sowerby, Trans. Lin. Soc, XIII, p. 468, pi. xxvi, fig. 2, 



1822. Syn. exclus. ; Gen. Shells, fasc., XIII, figs. 3-5, n. d. (1821 ?), 



(not. of Lam.). Ballast, North Africa. 

 Orbicula (s. g. Discina) norvegica Blainville, Diet. Sci. Nat., XXXII, p. 304, 



1824. Man. Mai., p. 515, pi. lv;, fig. 5, 1825 (not of Lamarck). 

 Orbicula (s. g. Discina) ostreoides Bang, Man. Moll., p. 263, 1829. 

 Orbicula ostreoides Reeve, Conch. Icon. Mon. Orb., No. 7, pi. 1, figs, la, lb, 



1862. 

 Discina ostreoides Lamarck, Hist. An. s. Vert., Ed. I, VI, p. 237, 1819. Ibid., 



Ed. II, VII, p. 297, 1836 (no description). — Thomas Brown, Conch, 

 extb., Ed. V, p. 108, pi. xiv, fig. 8, 1839. — Macgillivray, Ibid., Ed. 



IX, p. 124, pi. xiv, fig. 8, n. d. 

 Not Discina ostreoides Ttjrton, Dith. Brit., p. 238, 1822 (= Crania anomala). 

 Discina norvegica Crouch, Int. Lam. Conch., pi. xiii, fig. 2 * (fide Forbes and 



Hanley, II, p. 368). 

 Patella anomala Sowerby, Trans. Lin. Soc., XIII, p. 468, 1822, in synon. (not 



of Muller). 



When changes in nomenclature depend upon the identification of types 

 described by the earlier authors, the work is one of great difficulty, and 

 requires the utmost caution, lest fresh confusion be the result. In many 

 cases an approximation to a determination alone can be arrived at, and 

 authors may conscientiously differ as to the decision, and its bearings on 

 nomenclature. In the present case, however, there is but little difficulty, 

 as the species under consideration has been well described and carcfully 

 figured by the describers, though under several names ; the history of tbe 

 type specimens is very clear, and was put on record at the time. 



Lamarck constituted the genus Discina to receive a shell which he called 

 D. ostreoides, but of which he did not give any figure or specific description. 

 The specimen was received from Mr. J. Sowerby, and is the same species 

 and from the same lot of specimens, as the shell described by Mr. G. B. 

 Sowerby in the Lin. Transactions, and well figured by him there, under 

 the name of Orbicula norvegica. His very excellent figure enables mo to 

 speak with positiveness in saying that it is identical with Crania radiosa 

 Gould, of which the type specimens are before me. The figures of Schu- 

 macher are sufficiently exact to allow of identifying the species with his 

 Crania striata. The figures given by Reeve and Davidson are excellent, 

 and almost certainly represent the same species, though this is a matter of 



