BIVALVIA. 111 
Spec. Char. Testa minutd, obliqué, sub-ovati, valde inequilaterd, tumida ; antice 
productiore attenuata, 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, +th 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 PULCHELLUM, Jenyns. 
PrRA 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, pl. 12, fig. 151. 
— — Forb. and Hanl. Hist. Brit. Moll., vol. ii, p. 128, t. 37, figs. 12, 
13, 1849. 
—_ FONTINALE. Brown. Illust. Brit. Conch., 2d ed., pl. 39, fig. 23. 
- — Pfeiffer. Land und Sussw. Moll., pt. 1, p. 125, t. v, figs. 15, 16, 
1821. 
— oo Phil. En. Moll. Sic., vol. ii, p. 31, 1844. 
CycLas FoNTINALIS. Drap. Moll. Terr. et Fluv., p. 130, t. x, fig. 12? 
GALILEJA TENEBROSA. Da Costa. Corresp. Zool., fide Phil. 
Spec. Char. Testaé minutd, oblique-cordatd, valdé inequilaterd, ventricosd, concentrice 
striatd, tenui, fragili ; umbonibus prominulis. 
Shell small, obliquely heart-shaped, very inequilateral, ventricose, finely striated 
concentrically, thin and fragile ; umbones slightly prominent. 
Length, 4th of an inch. 
Locality. Stutton, Clacton, Grays (Pickering), Copford (J. 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. 
