1901.] XATUKAL SCIENCES OF PHILADELPHIA. (503 



defined, tending toward obsolescence. Before they have quite dis- 

 appeared, a sutural shelf sloping somewhat outward and bordered by 

 a slightly outward projecting margin appears; this very soon de- 

 velops into a serrated flange. At the same time the whorls become 

 almost smooth, the spirals usually only occurring on the narrowed 

 anterior portion or canal of the body whorl. Length of the adult 

 specimen figure 39 mm., diameter 18 ram. 



This is a parallel species to C. scalaris Lam. of the Paris Basin 

 (Calcaire Grossier) and C. longccvm Sol. of the London Clays 

 (Barton Beds). Compared with C. humerosus variety iexanus 

 Harris it has more ribs on the spii'e, which are more regular and 

 bulging, stronger spirals and the v.'ell -marked serrated flange. It 

 also differs somewhat in outline, the last whorl being broader than 

 the corresponding one of texanus. It differs from its European 

 parallels in many features, chief of which are the protoconch, the 

 long-ribbed spire, the character of the sutural shelf and flange, and 

 other points readily seen on comparison. 



From the Lower Claiboi-nian Eocene, Bald Mound, nine miles 

 southeast of Jewett, Leon county, Tex. 



Type No. 9,409, "Isaac Lea Collection of Eocene Mollusca," 

 Academy of Natural Sciences of Philadelphia. This species is 

 respectfully dedicated to Rev. L. T. Chamberlain, D.I)., Curator 

 of the Isaac Lea Collection. 



