24 TESTACEOUS MOLLUSCA. 



end ; white, nearly smooth ; shorter side a little gaping and with 

 a longitudinal wave ; tooth long, narrow, very oblique. f-^§.-- 

 U. States. Ossiculum not unlike tiro crescents joined at the ex- 

 tveniities. 



A Leana. Conr. Jour. A. N. S. Phil. 6. t. U. f. 11.— 

 CoCHLODESMA L. GouUl. Mas. f. 29, 30. Inequivalve, ellip- 

 tical, subcompressed, very thin and fragile, white with a yellowish 

 slightly polished epidermis, posteriorly rather shorter and slightly 

 more obtuse, with a linear gape ; margin waved, beaks very small. 

 \^.— U. States. 



A. Er.ONGATA. Stutch. Z. J. 5. t. .sup. 43. /. 9, 10. Trans- 

 versely elongated, inequivalve, inequilateral, pellucid, sinus of the 

 palleal scar elongated towards the anterior side, -x^.-i- 



A. Brevis. Stutch. Z. J. 5. p. 99. t. sup. 43./. 1, 2. -Pan- 

 dora B. Sow. Plano-convex, subtriangular, transversely striated ; 

 one valve convex, with two depressed transversely lamellated ribs on 

 the posterior extremity, the other slightly concave, the dorsal edge 

 inflected and inserted into a sulcus in the opposite valve; hinge with 

 an internal triangular cartilage, and a supervening shelly piece ; 

 umbo reflected posteriorly, f . -I- ^ 



' Can these four last shells be justly considered Anatinse ? 



Deshayes in his new edition of Lamarc introduces the genus 

 OsTEODOMA, which he thus characterises : Oblong, transverse, tri- 

 angular, thin, inequivalve, slightly gaping at its extremities ; hinge 

 linear, having on each valve a very narrow apophysis, firmly adherent 

 along the dorsal edge of the valves, and a quadrangular shelly sub- 

 stance kept between them by the ligament, to which its entire upper 

 surface adheres : muscular impressions small, the posterior one elon- 

 gated, the anterior rounded : palleal scar excavated posteriorly. 



0. CoRBULoiDEs.* Dcsh. — Mya Norv^^egica. Gmel. 3222. 

 D.p. 48.— Ch.f. 1647, S.— W. t. 2./. \3. — Tur. Blv. t.3.f. 6, 

 7. Ovate-oblong, rounded at one end, waved and truncated at the 

 other ; thin, inequivalve, semitransparent, white under a brown 

 epidermis, finely striated concentrically, beaks usually decorticated. 

 i..l.— iV. Europe. 



O. SoLEMYALis. Desk. — MvA S. Lam. 4. Transversely ob- 

 long, white, obtuse at the extremities, slightly gaping anteriorly, the 

 posterior side very short, the anterior more produced and obliquely 

 rayed. Wants but the hinge to make it a Solemya. — New Holland. 



0. Hyalina. Couthouy. — Gould Alas. f. 10. — Mya H. Conr. 

 Jour. A. N. S. Phil. 6. t. 11./. 12.— Lyonsia H. Conrad. Am. 

 C. t. 11./. 2. Oblong, extremely thin, fragile, pellucid, posteriorly 

 short and rounded, anteriorly produced, attenuated, slightly reflected 

 and truncated at the extremity, epidermis pale with radiating rugose 



