OF SANTO DOMINGO. 



255 



IS'earest to B. tarhata, but with the beaks much nearer the anterior end ; and Avith 

 tlie posterior end more produced and sloping. 



AXINyEA. Poll. . ' 



A. a c u t i c o s t a ta . Sby. sp. . , 



Peciunculus acuticostatus. Sby., Quart. Jour., Vol. VII., p. 511, pi. 10, lig. 13. - . . 



Id. Guppy, loc. cit., Vol. XXII., p. 293. 



A. pennacea. Lam. sp. . ' ' . 



Peciunculus pennacens. Lam., A. S. V. (Desli. Ed.) Vol. VI., p. 490. ■ ' . 



Id. Guppy, Quart. Jour. GeoL Soc, Vol. XXIL, p. 293. > ■ 



A. approximans. Gabb, n. s. • • ' - - - 



Shell small, obliquely sub-circular, posterior basal region slightly produced ; beaks small, almost in contact ; 

 area very small, not more than half as long as the shell and very narrow; surface marked by about forty stpiare ribs, 

 crossed by prominent lines of growth. Hinge strong, arched, teeth few ; basal and lateral margins crenulated, the 

 teeth corresponding with the external ribs. Diameter .4 inch. 



Recognizable by its slightly oblique form, numerous ribs, and unusually small 

 area. 



LIMOPSIS. Sassi. ,, . ■ . 



L. o V a 1 i s . Gabb, n. s. 



Shell obliquely oval, posterior portion of the base produced; beaks central, small, area moderate in size, smooth, 

 ligament jjit deep. Surface crossed by concentric ribs and finer radiating lines. Internal margin smooth ; liingo 

 strong, teeth few. 



About the size of the preceding species. This shell is remarkable for its oblique 

 form. Young specimens are nearly circular, but as they grow older the increase is 

 greater on the posterior side and base, so as to render the adalt outline decidedly 

 oblique. r . , , . 



NUCULA. Lam. ' 



N. t e n u i s c u 1 p t a. Gabb, ii. s. 



Shell minute, obliquely rounded triangular ; surface marked by very numerous minute radiating lines, barely 

 visible on some specimens ; inner margin minutely crenulated. Length 1 inch. 



jST. (Acila) t u b e r c u 1 a t a. Gabb, n. s. 



Shell obliquely rounded-triangular, convex ; anterior end nearly straight, base convex ; surface marked by 

 radiating stria and by small tubercles arranged in regular quincunx ; on both tlie anterior and posterior ends these 

 tubercles are replaced by rounded ribs which curve upwards to the margins. Anterior end occupied by a large luiiule 

 bordered by an impressed line. 



This peculiar little shell is distinguished by its remarkable sculpture. The 

 tubercles seem to be produced by the decussation of two sets of oblique ribs, under 

 all of which lie a series of finer strise radiating from the beaks to the base. 



LEDA. Schum. 



L. acuta. Gabb, n. s. 



Shell elongate, convex ; beaks central ; anterior end rounded, base broadly convex ; posterior end acute, hinge 

 slightly concave from the beaks to the posterior end. Surface marked by regular rounded concentric ribs. Length 

 .35 inch. 



YOLDIA. Moll. 



Y. oval is. Gabb, ii. s. 



Shell small, compressed, sub-elliptical ; beaks slightly iu ailvancc of the middle ; hinge line sloping gently, base 



