OF SANTO DOMINGO. 



257 



JANIRA. Sebum. 



.J. s o r o r. Gabb, n. s. 



Shell sub-orbicular, nearly equilateral, very inequivalve ; ears nearly equal ; right valve vei-y convex, left valve 

 concave ; surface marked by about twenty-two square radiating ribs, crossed by fine squamose lines of growth. 

 Length 1.9 inch. 



Allied to J. Jacoboius, J. maxima, and J. media, but diflferenc from them all in the 

 greater number and minutely squamose character of its ribs. 



PLEURONECTIA. Sw. 



P. p a p y r a c e a. Gabb, n. s. 



Shell discoid^l, sub-circular, very slightly longer than wide ; slightly inequivalve ; ears nearly equal ; surface 

 perfectly smooth, or marked only by faint lines of growth ; internal surface marked with small double radiating ribs. 

 Length from beak to base 2.2 inch, width 2 inches. 



A very distinct species, without any of the radiating lines of the living West 

 Indian smooth Pecten. 



SPONDYLUS. Lam. 

 S. Americanus. Lam., A. S. V., Vol. VIL, p. 185. 



My specimens agree perfectly with those from the coast of Florida, and usually 

 the lower valve is immensely developed, the spines small and frequently equaled in 

 size by transverse squamose plates. The upper valves usually bear long spines, not 

 much expanded. 



S. bostrychites. Guppy, Proc. Sci. Assn., Trinidad, 1867, p. 176. 

 8. hifrons. Sby. (not Goldf.), Quart. Jour. Vol. VI., p. 53. 



A beautiful convex, almost equivalve, Pecteniform species with remarkably narrow 

 areas and a thin shell. 



PLICATULA. Lam. 

 P. cristata. Lam., A. S. V, Vol. VI., p. 185. 



A single specimen in excellent condition and the valves yet in contact. 



ANOMIA. Linn. 

 A. ephippium. Linn., Syst. Nat., p. 1150. 



A single large specimen, nearly two inches in diameter. 



^ b OSTREA. Linn. 



O. Virginica. #rH^l> L^YT(«-eVWV 



This species is not rare, and usually grows to a length of about five inches. 



0. Hay ten sis. Sby., Quart. -Jour., Vol. VI., p. 53. 



0. Veatchii. Gabb, Pal. Cal., Vol. 11., p. 34, pi. 11, fig. 59 ; pi. 17, fig. 21. 



0. Virginica. Guppy (not Gruel), Quart. Jour. Vol. XXII., p. 577. 



Mr. Guppy is certainly wrong in considering this species even closely allied to 

 Yirginica. Hardly any two species in the genus are more I'emote from each 

 other. He must have confounded a plicate variety of O. Virginica, which is not 

 rare, with Sowerby's description. Thanks to an excellent lithographer, my figure in 

 Pal. California, pi. 17 of Vol. II., gives a very clear idea of the species. Although 



A. P. S. VOL. XV. OM. 



