BIVALVIA. 1 1 1 



Spec. Char. Testa minutd, obliqud, sub-ovatd, valde incsquilaterd, tiimidd ; antice 

 prodiidiore attenuatd, vel dimintiatd ; umbonibiis prominulis ef apjiendiadatis. 



Shell minute, oblique, sub-ovate, very inequilateral, and generally ventricose ; 

 anterior side much the longer ; umbones slightly prominent, furnished with a 

 projecting appendage. 



Length, yth of an inch. 



Locality. Clacton, Stutton, Cropthorn {Strickland), Grays {Pickering). 



Recent, Britain, Ireland, Germany. 



This is an abundant shell at the localities, Clacton and Stutton, where they are 

 often found with the valves united. 



The form is somewhat variable, but in general it may be described as triangularly 

 ovate, the posterior side being higher, that is from the umbo to the ventral margin, 

 diminishing towards the anterior side which is narrower and rounded, it is very 

 inequilateral and tumid, having at the umbo an appendage or projection, which is 

 its most distinguishing character. 



3. PiSIDIUM PULCHELLLfM, JeniJHS. 



Pera polchella. Leach, MSS., fide Jemjns. 



PiSIDIUM PULCHELLUM. Jemjns. Trans. Camb. Phil. Soc, vol. iv, p. 306, t. 21, figs. 1 — 5, 



1831. 

 _ _ Gray. Man. Land and f .-W. Shells, p. 284, pi. 12, fig. 151. 



_ _ Forb. and Hani, ffist. Brit. Moll., vol. ii, p. 128, t. 37, figs. 12, 



13, 1849. 

 — FONTINALE. Brown. Illust. Brit. Conch., 2d ed., pi. 39, fig. 23. 

 _ _ Pfeiffer. Land und Sussw. Moll., pt. 1, p. 125, t. v, figs. 15, 16, 



1821. 

 _ _ PhU. En. MoU. Sic, vol. ii, p. 31, 1844. 



Cyclas roNTiNALis. Brai). Moll. Terr, et Fluv., p. 130, t. x, fig. 12? 

 Galileja tenebrosa. Ba Costa. Corresp. ZooL, fide Phil. 



Spec. Char. Testa minutd, oblique-cordatd, valde incequilaterd, ventricosd, concentrice 

 striatd, tenui, fragili ; umbonibus jjrominulis. 



Shell small, obhquely heart-shaped, very inequilateral, ventricose, finely striated 

 concentrically, thin and fragile ; umbones slightly prominent. 



Length, \l\\ of an inch. 



Locality. Stutton, Clacton, Grays {Pickering), Copford (/. Brown). 



Recent Britain, France, Sicily. 



This appears to be by no means a rare shell in any of the above localities, though 

 it is less abundant than Hensloioianmn at the two former, and like the recent shell it 

 is subject to much variation. 



