INSTITUTE OF SCIENCE, PHILADELPHIA. 73 



Genus VOLUTOMORPHA Gabb, 1876. 

 Type F. Conradi Gabb, New Jersey. 



Of the three species referred to this group by Gabb, one, V. delawarensis 

 is an internal cast of doubtful relations ; V. cufaulcnsis Conrad, is known from 

 well-preserved specimens, and V. Conradi, although an internal cast, is with 

 little doubt congeneric with the V. eufaidensis* 



Vobitomorpha is sculptured very much like a worn Rostellites. It differs 

 from Rostellites in being covered with a thin glaze all over, and in having one 

 large "plait near the edge of the pillar instead of several subequal plaits. There 

 is sometimes an excavation behind the plait the posterior edge of which might 

 be mistaken for a second obscure plait. There is a notch or sulcus near or at 

 the suture, very strongly marked at the resting stages of the animal. The 

 nucleus is minute, polished, trochoid. The very young (not larval) shell has 

 all the characters of Piestochiliis Meek. The adult shell is thick, the pillar 

 straight ; in the mature shell the plait lags behind and is hardly perceptible 

 from the aperture ; while in Rostellites it is strong to the end, in the species I 

 have seen. 



These shells, like Rostellites, may reach a length of five or six inches. I 

 should add that in Conrad's restoration of Voliitilithes enfaulensis (Journ. Acad. 

 Phil., 2d ser., v. pi. 47, fig. 18) the sculpture is represented as much too sharp. 

 It has, on the whole, a feeble and obsolete look. Volutomorpha may be re- 

 garded as a link between Rostellites, Liopeplmn and Voliitilithes, combining 

 some of the features of each. Ptychosyca Gabb may be a synonym. There 

 are a large number of nominal species, based on casts, from New Jersey, etc., 

 which may belong to this group. 



Genus Liopeplum Dall, 1890. 

 Plate 6, figures 12, 12 a. 

 {Lioderma Conrad 1865, not Marseul, 1S57.) 

 Type L. {Athleid) lioderma Conrad, op. cii. pi. 46, fig. 32. Ripley Sands, uppermost Cre- 

 taceous of Mississippi. 



Lioderma Conrad, beside the type, includes Voliitilithes cretacea and " Conus " 

 canalis Conrad, as well as two or three elegant and still unpublished species 

 in the National Museum collection. It seems, so far, to be confined to America. 

 The name is preoccupied in Coleoptera, and I suggest in its place the name 

 Liopeplmn. 



Liopeplum is of smaller size than the two preceding groups. It is charac- 

 terized by a minute trochoid nucleus, ribbed early whorls and smooth body- 

 whorl in the adult, all covered with a most elegant and polished glaze ; also 

 by its habit of depositing a band of callus above the suture on the periphery of 

 the preceding whorl. The pillar is stout and slightly curved, and the plaits 



* By a typographical error Proc. Phil. Acad. Sci. 1876, p. 290, cretacea is printed instead of 

 reference to plate and figure settles the species meant. 



