9 8 



Bulletin 35 



Page 177 



§ 4. Descriptions of some Species of Westindian 

 moleuska. 



I take advantage of the present opportunity to give sketches 

 and descriptions of five shells, two of which have been pre- 

 viously described, but not figured ; the other three are new. 

 Of the five, four are inhabitants of the Gulf of Paria, and 

 the fifth is a small but curious shell from the miocene of 

 Jamaica. Metula lintea and Periploma orbicularis were 

 dredged in the Gulf of Paria by Mr. W. O. Crosby, of the 

 Boston Society of Natural Histor}-. Mr. Crosby discovered 

 not only the species mentioned in this communication as 

 dredged by him, but several others which he kindly com- 

 municated to me, and which, are of remarkable interest as 

 being either identical with, or nearly allied to fossils of the 

 Westindian miocene. As the specimens referred to are all 

 dead shells, devoid of colour, it has occurred to me as a 

 possibility that they might have been derived from some 

 tertiary bed at the bottom of the Gulf. An hypothesis like 

 this, however, would be at once refuted by the finding of a 

 single living example. 



1. Periploma orbicularis n. sp. (PI. vii., f. 13). 



Suborbicular, subequilateral, somewhat compressed, thin, 

 nacreous internally, shagreened externally by minute rugo- 

 sities disposed in radiating lines, and covered with a thin 

 epidermis ; anterior side regular^ rounded ; posterior side 

 somewhat produced, sinuate, and obliquely truncate; umbones 

 prominent, fissured. Height 25 mill., length 30 mill. 



Resembles the Periplovia compressa of D'Orbigny (Voy. 

 Amer. Merid., p. 514, pi. lxxviii., f. 19, 20), but having a 

 greater relative height from the umbo to the margin, is more 



