BIVALVIA. 101 
Mysca pictorum. Turt. Brit. Biv., p. 245, 1822. 
— ODesuayesi. Brown. Illust. Brit. Conch., p. 81, pl. 32, figs. 1—4. 
— — Rossm. Icon. Land und Sussw. Moll., p. 23, pl. 13, fig. 197. 
— .onerrostris. Ziegl. in Rossm. Iconog., pt. 3, p. 26, pl. 14, fig. 200, and pt. 12, 
pl. 54, fig. 38. 
Ency. Meth., t. 248, fig. 4. 
Spec. Char. Testé transversd, elongata, subovatd, inequilaterd, anticé rotundata, 
posticé, angulata, vie rostrata ; margine dorsali et ventral subrectd. 
Shell transversely ovate, elongate, inequilateral ; anterior side rounded, posterior 
angulated, scarcely rostrated ; dorsal and ventral margins nearly straight. 
Length, 2 inches. 
Locality. Grays, Cropthorn. Recent, Britain, France. 
This shell appears very rare as a British fossil; one specimen in the cabinet of 
Mr. Pickering is of a form that may be determined without much hesitation as belong- 
ing to this species, and resembles rather the thinner variety of the recent shell. The 
principal or perhaps only difference observable between this and the preceding species 
in the fossil state, is a more elongated dorsal area, less sloping on the posterior side, 
so that the ventral margin is more parallel with the upper edge than in U. tumidus. 
A specimen in the British Museum, from the same locality, seems to possess the like 
determinable characters, and one in the Museum of the Geological Society, presented 
by Mr. Strickland as from Cropthorn appears to be of this species. These specimens 
are all that I have seen, they mostly resemble fig. 766, Rossmasler. 
Anoponta, Cuvier, 1798. 
Muscuuuts (sp.). Lister. Cristarta. Schum., 1817. 
Mytiuts (sp.). Linn. Srropuitus. Rafinesque, 1820. 
Linn, and LimnmopERMa (sp.). Poli, LasTENA. Id. 
1791. Sympuynora (sp.). Lea., 1832. 
AnopontitEs. Brug., 1799. Opatrnia. Rafinesque, 1832. 
Driesas. Leach, 1814. LamproscarHa. Swains., 1840. 
Appius. Id. MSS., fide Gray, HeEmiopon. Td. 
Anopon. Oken., 1815. PATULARIA. Id. 
Generie Character. Shell equivalve, inequilateral, ovate, transverse, usually thin, 
more or less eared, and closed; smooth, and in the recent state covered with an 
epidermis generally eroded at the umbones. Hinge linear, edentulous, or with one 
elongated lamina on the posterior side. Ligament external. Impression of the mantle © 
without a sinus. 
The animal of this genus closely resembles that of the preceding one, being furnished 
with a large fleshy, compressed foot, and the hinder part of the mantle is ornamented 
with short and pointed tentacles; anal opening is large, and the margin plain. 
