MUSEUM OF COMPARATIVE ZOOLOGY. 29 



>~ Orbicularius Dumeril, Zool. Analyt., p. 1G8, 1806. 



= Distinct sp. Turton, Dith. Brit., p. 238, 1822 (Gen. diag. exclus.). 



= Anomia sp. Linne, Syst. Nat., Ed. X, I, p. 700, 1760 ; Ed. XII, p. 1150, No. 

 216, 1767. — Gmelin, Syst. Nat., p. 3340, 1792. — Chemnitz, Conchyl. 

 Cab., VIII, p. 72, 1785. — SchrGter, Einl., Ill, p. 381, 1778.* — Poli, 

 Test, utriusq. Sicil., II, p. 189, 1795. — Dillwyn, Cat. Shells, I, pp. 285, 

 286, 1817. 



= Anomites sp. Davidson, Me'm. Soc. Lin. Norm., X, p. 226, 1856, in syn. 

 (not of Linne, Syst. Nat., 1768). 



= Patella sp. O. F. Muller, Prodr. Zool. Danica, p. 237, No. 2870, 1776 ; 

 Zool. Danica, I, p. 4, 1788. — Gmelin, Syst. Nat., p. 3721, 1792. — Mon- 

 tague, Trans. Lin. Soc., XI, p. 195, 1808. — Humphrey (ubi ? fide Sby. 

 and Rve). — Koch and Dunker, Beitr. Ool.-Geb., p. 51, 1837. — 

 Puemer, Verst. Ool.-Geb., p. 135, 1840. 



= Terebratula (part) Schweigger, Naturgesch., p. 690, 1820* (fide Gray, An. 

 Phil., 1-825). 



= Producta 1 sp. Klipstein, Beitr. Ost. Alp., VIII, pp. 60, 239, 1843. 



= Siphonaria sp. Quenstedt, Handb. Petref., I, p. 442, 1852! 



= Numulus Agassiz, Nomencl. fasc, IX, p. 60, 1846. 



= Siphonotreta sp. Eichwald, Zool., I, p. 274, 1829 * (fide Bronn 1. c.) 



= Criopododerma Agassiz, Nomencl. Ind., p. 301, 1848 (corr. Poli). 



= Criopus Gray, Lond. Med. Repos., 1821 * (fide Herrm., Agassiz) —Flem- 

 ing, Phil. Zool., II, p. 499, 1822, and Brit. An., pp. 367, 377, 1828. — King, 

 Perm. Foss., p. 84, 1849.— Leach (Gray), Moll. Gt. Brit., p. 358, Dec. 

 1852. 



= Cryopus Deshayes, Hist. An. s.Vert., VII, p. 314, 1836. 



Shell with or without a more or less produced beak and false area in 

 the lower valve. The two posterior muscular impressions are near the 

 cardinal border, and usually larger and more widely separated than the 

 two anterior scars. The latter are near the centre of the valves, and in 

 the lower valve are confluent in front, or barely separated by a small nose- 

 like prominence, or rostellum, which is usually excavated at its most ele- 

 vated extremity for the attachment of a muscle, which at its other end is 

 attached near the cardinal border of the upper valve between the post- 

 adductor scars ; the shelly matter being slightly produced on each side of 

 this attachment in some species, forming two slight tooth-like prominences. 

 Margin of the shell more or less tuberculous or papillose. Lower valve 

 differing in position and extent of attachment to extraneous objects. 

 Upper valve conical, with the apex subcentral ; internally vaulted, simple, 

 without apophyses or septa. Lower valve without septa or apophyses, 

 unless the rostellum be so considered. Exterior foliated, concentrically 

 or radiately striate, or smooth. Great pallial sinuses leaving more or less 

 flabeliiform or paucidigitated impressions on the shelly matter, which im- 

 pressions are not confluent anteriorly. 



