BIVALVIA. Ill 



Spec. Char. Testa minutd, obliqud, sub-ovatd, valde incequilaterd, tumidd ; antice 

 productiore attenuatd, vel diminuatd ; umbonibus prominulis et appendiculatis. 



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. PlSIDIUM PULCHELLUM, Jenyns. 



Pera pulchella. Leach, MSS., fide Jenyns. 



Pisidium pulchellum. Jenyns. 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. Hist. 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. 

 _ _ Phil. En. Moll. Sic., vol. ii, p. 31, 1844. 



Cyclas fontinalis. Brap. Moll. Terr, et Fluv., p. 130, t. x, fig. 12? 

 Galileja tenebrosa. Da Costa. Corresp. Zool., fide Phil. 



Spec. Char. Testa minutd, oblique-cordatd, valde inaquilaterd, ventricosd, concenirice 

 striata, tenui, fragili ; umbonibus prominulis. 



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

 concentrically, thin and fragile ; umbones slightly prominent. 



Length, ith 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 Henslowianum at the two former, and like the recent shell it 

 is subject to much variation. 



