48 TESTACEOUS MOLLUSCA. 



anterior side the longer attenuated and slightly truncated : ventral 

 edge slightly incurved. |. — Rochelle in rocks. ^ 



PANDORA. 



Shell reyular, inequivalve, inequilateral^ and transversely oblong ; 

 upper valve Jfattened, and the under one convex ; hinge with 

 two oblong diverging cardinal teeth, in the upper valve, and the 

 other valve with two oblong grooves ; ligament internal. 



P. Obtusa.* Lam. 2.— Sow. Sp. Con.f. 1, 2, 3.— Del. t. 4. 

 f. 8. — Tkllina Pinna. Pennant, t. 67-f' 3. — Solen. P. 

 Mont. t. 15. /'. 3. — W. t. 3.f. 35. Ovate, posterior side very short, 

 obtuse and obliquely rounded ventrally, slightly angular dorsally : 

 narrower than the anterior which is much lengthened and 

 dilated : posterior dorsal edge nearly straight and angulated at the 

 end, dorsal edge of the flat valve over-lapping the concave one. 



P. RosTRATA.* Lain. 1. — Sow. G. — So7v. Sp. Con.f, 7, 8, 

 9.— Tellina Inequivalvis. Lin. 1118. — D.p.86. — I)on. t. 

 41./. \.—Turt. Biv.t. 3./. 11. to U.—E. t. 250./. l.—Ch.f. 



^ It is scarcely possible from the imperfect description, to decide 

 whether this shell is the Anatina Truncata of Turton, or a Sphaenia. 

 I give the characteristics of the former from Turton. 



A. Truncata.* Tnrt. Biv. p. 46. t. 4./. G. Convex, wedge- 

 shaped, slightly angular and truncated anteriorly, abruptly truncated 

 posteriorly, rough, transversely striated ; ventral edge nearly 

 straight : teeth projecting a little inwards but running obliquely. — 

 Enrjland. 



Mr. Reeve in his systematic Conchology, has placed as ap- 

 proximating to this genus, 



MYOCHAMA. Stutchbury. 



Inequivalve, adhering ; the attached valve with two unequal diverging 

 marginal teeth, separated at the umbo by a triangular pit, in which 

 one end of a testaceous appendage is inserted and connected by a 

 horny cartilage ; the free valve with two unequal small diverging 

 teeth close under the umbo, in which is inserted the other end of 

 the testaceous appendage. Umbo of the free valve curved inwards, 

 that of the fixed valve outwards. Muscular impressions two, nearly 

 orbicular, distant, lateral ; palleal scar with a short broad sinus. 

 Ligament thin, external. 



M. Anomoides. Stutch. Z. J. 5. sup. t. 42. /. 1, to 4.— 

 lieeve. t. 39. Rose coloured, thin, with prominent radiating dichoto- 

 mous ribs. Free valve extremely convex, the umbo projecting beyond 

 the apex of the other ; epidermis thin and transparent. 7^j..-jl' 



