Maryland Geological Survey 429 



35°; posterior fourth of the whorl sharply constricted and oppressed, cut 

 off from the portion in front of it by a shallow sulcus; body whorl broadly 

 rounded, evenly contracted at the base and merging gradually into the long, 

 gently recurved pillar; external sculpture reticulate; axials in the form 

 of sharp, abruptly and very prominently elevated axial ridges, sepa- 

 rated by narrowly flattened, or feebly concave intercostals approximately 

 seventeen in number on the later whorls, uniform in character from the 

 fasciole to the anterior suture, interrupted at the margin of the fasciole 

 and a little less elevated upon it, persistent on the ultima to the base of 

 the pillar ; spiral sculpture probably uniform in character over the entire 

 surface and overriding the axials; spirals cordate, obtusely angulated, 

 equisized and equispaced, the interspirals concave, and a little narrower; 

 spirals about seven in number upon the later whorls of the spire — three 

 upon the fasciole and four in front of it — and probably about twenty on 

 the body and pillar, excluding the secondaries which are introduced near 

 the base of the body ; suture lines deeply impressed ; character of aperture 

 and number of columellar plications not known. 



Dimensions. — Altitude 43 mm., maximum diameter 15 mm. 



The apparent similarity of this species to Volutomorpha conradi 

 (Gabb) in the general contour and character of the ornamentation has 

 led to its assignment to this genus, although the discovery of further 

 material may prove the reference incorrect. V. perornata is described from 

 a cast of the exterior surface which has served as the unique type. It 

 differs from V. conradi in the smaller size, posteriorly constricted and 

 tabulated whorls and sharper, more prominently elevated, axial sculpture. 



Occurrence. — Monmouth Formation. Brightseat, Prince George's 

 County. 



Collection. — Maryland Geological Survey. 



Genus LIOPEPLUM Dall 

 [Trans. Wagner Free Inst. Sci., Pliila., vol. iii, pt. i, 1890, p. 73] 

 Type. — Liopeplum lioderma Conrad. 



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

 characterized by a minute trochoid nucleus, ribbed early whorls and 



Etymology: \eios, smooth; jre'7rXos. an upper garment. 

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