Maryland Geological Survey 439 



aperture is rather narrow and lenticular in outline behind the canal ; the 

 outer lip is thick, sharp and symmetrically arcuate, the inner evenly con- 

 cave ; the characters of the canal are not known. 



Dimensions. — Altitude of spire 45 mm., maximum diameter of body 

 28.5 mm. 



It is to be hoped that a specimen may be collected in the near future 

 which may be worthy to serve as the type of this remarkable species. 



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

 County. 



Collection. — Maryland Geological Survey. 



Genus PIESTOCHILUS Meek 

 [Check List Inv. Fossils, N. A., Cret. and Jur., 1864, p. 22] 



Type. — Fusus scarboroughi Meek and Hayden. 



" Differs from the typical species of Clavellithes in having the aperture 

 acutely angular behind, in consequence of the outer lip being closely 

 appressed to the body whorl above, instead of forming a kind of posterior 

 canal; and in having the inner lip thin instead of thickened above." — 

 Meek, 1864. 



Twelve years later, with the aid of further material, he redescribed and 

 discussed the genus as follows : 



" Shells of small size, with spire and canal produced ; volutions flattened 

 or moderately convex and finely spirally striated, sometimes with vertical 

 folds; plait or plaits of columella not exposed in a direct view into the 

 aperture, very oblique, and occupying a higher position than in either 



of the foregoing; outer lip smooth within The type of the group 



Piestochilus was originally referred provisionally to the genus Fusus. 

 when only imperfect specimens, merely showing its form and surface 

 markings, were known. Subsequently, on examining others, I was led to 

 the conclusion that it could not be a true Fusus, and thought, from its 

 general appearance, that it was at least more probably related to Clavel- 

 lithes of Swainson. In removing it doubtfully, however, to the latter 

 genus, I was strongly impressed with the belief that it would at least form 



Etymology: wiesros, compressible; x 6 '^ os > ^P- 



