Maryland Geological Survey 401 



an equal number near the base of the body ; faint incremental striations 

 also discernible under magnification ; suture lines impressed ; body whorl 

 broadly and feebly convex, rather abruptly constricted at the base ; aperture 

 more than half as high as the entire shell, broader and somewhat patulous 

 anteriorly; outer lip strongly varicose, the varix produced backwards 

 almost or quite to the suture line ; inner lip arcuate, strongly constricted 

 at the base of the bodv, heavily calloused, bearing two conspicuous folds. 

 a horizontal plait at the base and an oblique marginal plait not quite so 

 prominent as the one behind it; parietal wash heavy, its margin sharply 

 defined and not reaching the posterior commissure ; base deeply emargi- 

 nate. 



Dimensions. — Altitude 10.2 mm., maximum diameter 7 mm. 



Type Locality. — Brightseat, Prince George's County. 



The form is well characterized by its squat outline, conspicuously vari- 

 cose outer lip and prominent columellar folds. 



This interesting and abundant species is named in honor of Prof. 

 William Bullock Clark of Johns Hopkins University, and the head of 

 the Geological Survey of Maryland. 



Occurrence. — Monmouth Formation. Brightseat, Brooks estate near 

 Seat Pleasant, and Friendly, Prince George's County. 



Collection. — Maryland Geological Survey. 



Genus CINULIA Gray 

 [Syn. Brit. Mus., 1840, pp. 62, 90] 



Type. — Auricula globulosa Deshayes. 



Shell more or less globose ; spire very low, sometimes abruptly attenu- 

 ated ; external surface spirally lirate or striate ; aperture narrow and some- 

 what arcuate; margin of outer lip much thickened but smooth within; 

 columella very short, bearing a single, anteriorly produced plication; 

 anterior emargination obsolete. 



Cinulia is separated from Avellana by the development of a single col- 

 umellar plication instead of two, three or four, by the uniform absence of 

 denticles upon the inner surface of the labrum, and by the obsolete ante- 

 rior notch. 



The genus is restricted in its known distribution to the Cretaceous. 



