310" TESTACEOUS MOLLUSCA. 



disposed throughout in numerous and regular rounded folds. Valves 

 very unequal in convexity, but equal in length ; the lower one pro- 

 found ; the upper one depressed, and divided into flattened ribs by a 

 few broad grooves, its entire surface covered with numerous appressed 

 imbricated lamellae. Inside whitish, the elongated denticles extending 

 nearly or quite round the margin of the upper valve : scar oboval or 

 suborbicular, rather large. % Philippines. In all the examples 

 I have seen, the hinder side of the lower valve was the more elevated. 



O. Pyxidata. Adams, Samar. p. 72, t. 21, /. 19. Orbicular, in- 

 equivalve, dirty brown ; both valves with radiating nodulous ribs, 

 which in the extremely convex lower one are oftentimes double ; upper 

 valve flat : ventral edge crenulated. 1. Philippines. 1 



VULSELLA. 



Longitudinal, subequivalve, unattached, usually imbedded in sponge, 

 pearly within; beaks of equal length. A rather prominent hinge- 

 callosity, in each valve, flattened above and stamped with an obliquely 

 arcuated conic cartilage-pit. 



V. Lingulata. (Kn. 5, t. 2, / 1 to 3.)— Mya V., Lin. 1113.— 

 Ch.f. 11.— P.p. 56.— V. L., Lam. l.—E. t. 178,/. 4.— Sow. G.— 



Reeve, C. S. t. 108. — Osteea V., W. t. 11, /. 84. Large, elongated 



1 Compare with the above the 0. Mordax, Discoidea, Glomerata 

 and Circumsuta of Gould (Proc. Bost. iii.), the O. Spreta of 

 D'Orbigny {Cuba), and the O. Chllensis of Philippi (Kust. ed. Ch. vii. 

 1, t. 13).' 



See, too, 0. Gigantea of Thunberg (Suecice Nov. Act. 1793), 

 a coarse elongated oyster with depressed lamellae from Japan ; 

 O. Forskalii (Ch. 8, p. 30, f. 671, copied W. t. II, f. 66), quoted by 

 Philippi, and probably aright, for 0. Cornucopia, 0. Corbiculus 

 (Ch. 8, p. 44, f. 680. — O. Orbicularis, PH. 278, not of Linnaeus, 

 whose species was inadequately defined. — W. t. 11, f. 70); and 

 O. Capsa of Fischer (Mus. Pemid.) from Le Garin of Adanson 

 (Sen. t. 14,/. 2). 



O. Dentifera, Crocea and Elliptica of Dufo (An. Sc. Nat. 

 ser. 2) cannot be recognised by their descriptions. O. Papyracea 

 of Gmelin (3337) and 0. Pauciplicata of Deshayes (Moree) are 

 evidently immature ; O. Semicylindrica of Say (Jour. Ac. N. S. 

 Philad.), an accident of growth. The 0. Ovalis of Gmelin is 

 solely taken from Schroter's ' Einleitungen,' vol. iii. p. 378, t. 9, 

 f. 8. 



