OCECUM. Panama Shells, 161 



211. Cflccum diminutum. Nov. sp. 



Shell well arcuated, slender, witli tlie diameter uniform, 

 except near the summit: white: with about 17 stout rings, 

 which are rather distant and are but slightly flattened at the 

 summits, followed by about 10 rings which are small and less 

 prominent : apex lateral, not prominent. 



Length .06 inch ; breadth .018 inch. 



Station. — Unknown. 



Habitat. — Panama ; 0. B. A. 1 

 1 specimen was found. 



212. Caecum eburneuin. Nov. sp. 



Shell rather slender, well arcuated, scarcely widening towards 

 the aperture, slightly contracted at the summit : ivory white : 

 with about 33 broad stout approximate rings with flat summits ; 

 with the first 4 to 10 rings and sometimes the last 2 or 3, very 

 prominent and less approximate, and the rest slightly promi- 

 nent and closely approximate : apex prominent. 



Length .09 inch ; breadth .025 inch. 



A var. (?) has only 24 rings, of which the last 8 or 4 are pro- 

 minent, indicating maturity. 



Station. — Unknown. 



Hahitat. — Panama ; C. B. A. I 



22 specimens were found in the sand. 



213. CoBcnin firmatum. Nov. sp. 



Shell rather stout, well arcuated, widening towards the aper- 

 ture, moderately contracted at the summit : ivory white : with 

 about 25 very stout broad prominent not closely approximate 

 rings, with flat summits : apex not very prominent. 



Length .09 inch ; breadth .03 inch. 



JULY, 1852. 41 AiiM. Lto. Nat. Hist, 



