OP SANTO DOMINGO. 



239 



A very small shell, recognizable by the rounded body wliorl and slightly angular 

 upper volutions, and by the short, open canal. 



C. Maoiiusis. Gabb, n. s. 



Shell minute, •whorls rounded, with a few obsolete rounded varices ; upper whorls smooth, others crossed by 

 fine regular revolving lines ; aperture broad, canal very short, columellar twisted, outer lip prominent in front, simple. 

 Length .G inch. 



Most nearly allied to C. simplex^ of which I was at one time inclined to consider 

 it the young. But its more slender form forbids such a reference. The apical angle 

 of that species is double that of the present, and both are very constant. 



CERITHIDEA. 'Swains. 



C. minuta. Gabb, n. s. 



Shell minute, stout, spire about twice as long as the aperture, whorls seven or eight, very slightly convex on the 

 sides, suture linear. Surface marked by numerous fine longitudinal ribs covering the spire and extending to the mid- 

 dle of the body whorl. These are crossed by finer revolving lines, most marked in advance. Canal nearly obsolete, not 

 emarginate, inner lip encrusted, outer lip thickened and produced in advance. Aperture acute behind. Length .3 

 inch . 



Very rare ; but a single example found. ' . ' 



TRIPHORIS. Desh. , ..... 



T. n 1 g r o c i n c t u s? Adams, sp. ■ ' ' . 



Cerithium, id. Adams, Best. Jour., N. Hist., Vol. II., p. 286, pi. 4, fig. 11. •. •. • '>'. 



Triforis, id. Stimp., Sm. Check List. ■ . ^ , , , . 



I am by no means sure of my identification of this species ; my only specimen being- 

 immature and barely more than .05 inch in length. But it seems to agree as nearly 

 with that, as with any other species ; and I should not venture on more than a pro- 

 visional determination v/itli such imperfect matei ial. 



BITTIUM. Leach. 



B. asperoides. Gabb, n. s. 



Shell elongate, slender, whorls convex, marked by numerous longitudinal ribs, crossed by from three to five sharp 

 filiform ribs, sometimes with finer lines interposed ; base striate ; aperture sub-quadrate. 



Close to B. asjjerum of the coast and late Tertiaries of California, but more robust, 

 with more longitudinal ribs and with a shorter mouth. 



B. c a n a 1 i c u 1 a t u m . Gabb, n. s. 



Shell elongate, slender, spire high, whorls eleven, slightly convex, suture channeled, surface marked by numer- 

 ous, fine closely-placed longitudinal ribs, crossed by obsolete revolving lines. Aijerture rounded sub-quadratc. 

 Length .2 inch. 



Differs from the preceding by its channeled suture and by the absence of cancel- 

 lation on the surface. From the following species it is distinguished by its smaller 

 size, more delicate structure, l)y the presence of the channel and by the much more 

 numerous whorls. 



B. costatuni. Gabb, n. s. 



Shell minute, robust, whorls seven or eight, llattcncd on tlio sides, s\iturc linear. Body wliorl jiroduced in ad- 

 vance. Surface marked by numerous large longitudinal ribs whirh begin at the suture and co\ cr the whole surface. 



