/ 4 PROPILIDIUM. 



Jeffr. but less regularly elliptical, more lengthened, narrower behind ; 

 the altitude less in proportion to the greatest diameter, the apex a 

 little more anterior, surface less ornamented. 



P. PERTENUE Jeffreys. PI. 40, fig. 49. 



Shell oval, convex, very thin and delicate, transparent, and 

 glossy; sculpture, none ; color whitish ; beak small, cylindrical, and 

 incurved, forming a minute spire of two whorls ; mouth oval ; mar- 

 gin even ; inside glossy; septum small. 



Length O'l, breadth 0-075 inch. {Jeffr.) 



Off Rinaldo's Chair and Palermo, Mediterranean 162t fms. 

 Off Mode Island, 640 fins. 



P.pertenue Jeffr., P. Z. S. 1882, p. 674, t. 50, f. 7.— Verrill, 

 Trans. Conn. Acad, vi, pp. 262, 271. — Dall, Blake Gastrop., p. 412. 



The young shells of P. ancyloides are much smaller than the species 

 now described, are more expanded or depressed, and have the same 

 sculpture as the adult ; they are also proportionally solid as well as 

 of a dull hue. 



The inner layers of most of the specimens are permeated by a 

 microscopic and branching spore-like organism, perhaps of a fungoid 

 nature. 



An imi:)erfect specimen of another small and apparently distinct 

 species occurred also in Station 17. It has the characteristic septum, 

 but otherwise resembles a Lepetella. The beak is ver}' much shorter 

 than in P. pertenue ; and the spire has barely one turn. 



I have originally given the species above described the ms. name 

 tenue. (Jeffr.) 



The identity of the specimens collected off Rhode Island, by Prof. 

 Verrill, is not certain. 



P. coMPREssuM Jeffreys. PI. 40, fig. 50. 



Shell differs from P. pertenue in being oblong intead of oval, and 

 in being laterally compressed like Patella (Lepetella) latero-com- 

 pressa of Rayneval, a Monte Mario fossil, and, according to Dr. 

 Tiberi, living in the Bay of Kaples ; and it is also not quite smooth, 

 but is marked by a few slight longitudinal strise ; the beak is pro- 

 portionally longer, somewhat twisted to one side, and nearly over- 

 hangs the hinder margin, instead of being placed (as in P. pertenue) 

 at about one-third of the distance from it. 



Length 0-1, breadth 0-065 inch. (Jeffr.) 



North Atlantic. 



