BAHAMA MOLLUSKS AND BRACHIOPODS. 



17 



arched basal margin, and straight slopes diverging about 90 

 from the beaks; sculpture of 10-12 rounded nodulous radiat- 

 ing riblets with narrower inter-spaces crossed by rather 

 prominent incremental lines: internal basal margins strongly 

 crenulated by the sculpture; hinge line narrow and feeble, liga- 

 ment largely immersed; resilium small subumbonal. Height 

 of shell 2.0; length 2.0; diameter 1.0 mm. 



Habitat: Bermuda, received from Prof. R. P. Whitfield, 

 collected by Miss Peniston on the beach. Types, American 

 Museum of Natural History, Central Park, New York City. 

 and United States National Museum. No. 107.365. 



The occurrence of this little shell at Bermuda is very inter- 

 esting as the genus was originally described from Port Rosa- 

 rio, Patagonia, in two to thirty fathoms, other species being 

 known from the west coast of South America, Tristan 

 d'Acunha, the Cape of Good Hope, and Australasia. The 

 present species, is, I believe, the first described from the 

 northern hemisphere and is respectfully dedicated to Mr. 

 Edgar A. Smith, Assistant to the British Museum, the author 

 of the genus. 



From the Patagonian tvpe. C. pallida Smith, (P. L. S. 

 1SS1, p. 43, pi. v. figs. 9, a-b), this differs by its more triangu- 

 lar shape, fewer ribs, and smaller size. All the other species 

 are even less similar. C. smithii looks very much like a minia- 

 ture edition of Cardita (P/eurowcr is) trident at a Say, but a care- 

 ful scrutiny of numerous specimens of the latter species gives no 

 evidence of the existence of any separate resilium, the ligament 

 and resilium being joined in the ordinary way as a single organ, 

 rather deeply sunken and allowing only a narrow lineal portion 

 to be visible externally between the edges of the closed valves. 

 The same is true of Cardita dominguensis Orb. and the curious 

 Cardita radians Conrad {+ flabella Conr. 1S46, non Reeve, 

 1S43 + Venericardia obliqaa Bush) and it seems in spite of 

 their marked differences of form as if there was no ground 

 for referring either of the three to any group w r hich will not 

 receive the others. 



IV— 1 



