I:I.M 221 



ha- a shallow rounded notch, the outer boundary of whose path is 

 marked by tin- -uminit of a raised line ; anterior part of aperture 

 wider, imt very oblique, rounded in front ; outer lip .-traiirht, thin, 

 arched forward in tlie inid.lle ; pillar thin, simple, with no trace of 

 a plait: 1> >dy without percept ihle callus ; behind the pillar a small 

 very deep umbilical perforation ; apex nearly flat, hounded by the 

 above mentioned raised line, within which the fa-ei<>le of the notch 

 is rounded over but does not reach the level of the line referred to ; 

 nucleus somewhat depressed, but not deeply: about three and a 

 half whorls are visible on the apex. Max. Ion. of shell 4*0 ; max. 

 lat. 2-5; lat. of apex 1'5 mill. (DalL). 



}\'esi Indies (U. S. Fish Commission), probably from near ]}<ir/i- 

 tlii.*, in about 80 fms., sand. 



rti-im/ni pervins DALL, Blake Gastr. p. 48. 



This species is remarkable for its deep though minute umbilicus 

 and its dish-like apex. Its general form is not unlike U. per plica- 

 ins, l)ii t the sides are straighter and the other characters quite dif- 

 ferent. The locality is unfortunately doubtful though it was some- 

 where in the Antilles (Ball.). 



R. OMPHALIS Morch. Unfigured.. 



Shell subcylindrical, short, slightly contracted in the middle, with 

 obsolete growth strife, regular and elega-ntly expressed toward the 

 spire ; spiral stria? very obsolete, irregular. Spire openly umbili- 

 cated, surrounded by a white pellucid line. Aperture very narrow 

 posteriorly, dilated anteriorly ; columella straight, thick ; external 

 margin acute. Alt. nearly 4, diam. 2 mill. (M). 



St. Thomas (Riise). 



Retiisa omphalis MORCH, Malak. Bl. xxii, p. 172, 1874. 



Not dissimilar from Cylichnella hidenfnfu. but larger, thinner, 

 with umbilicate spire and straight columella, etc. (.17. 



R. SULCATA Orbigny. PI. 23, figs. 73, 74. 



Shell cylindrical, white, dilated below, thin, pellucid, longitudi- 

 nally sulcate, truncated at summit and concave, the spire umbili- 

 -cated. Aperture linear, suddenly dilated below. 



Alt. '2, diam. 1 mill. 



Cape Hatteras ; )fV.</ Indies, 14-31 fms. 



Jin Ha sulcata ORB., Moll. Cuba i. p. 129, pi. 4 bis, f.9-12. I 

 c///f/x i U< 'tn.-ni) snlcata DALL, Blake Gastr. p. 45 ; Cat. Mar. Moll. 

 S. E. U. S., p. 8<i. 



