198 



than those of the preceding species, and of which there are sixteen 

 on the inferior whorls ; base of last volution having two revolving, 

 rounded, varicose carinas and several fine revolving raised lines be- 

 tween the carinte and columella. The longitudinal folds do not cease 

 at the carinas as with the preceding species, but are continued to the 

 columella. 



Spiral angle, 32° ; length, 0.25 inch ; width, 6.13. 



Distinguished from the preceding species by its smaller and more 

 numerous longitudinal folds, and its two revolving carinas at base. 



Locality same as the last. 



Genus Pleurotomaria, Defrance. 



P. AusTiNENSis, (n. sp.) Shell large, depressed conical, spire 

 short, very rapidly expanding from apex ; volutions five, convex ; last 

 one subangulated below, and very gently convex beneath ; an ob- 

 scure, rounded, revolving ridge near the suture, and a narrow carina 

 (band of sinus) a little above the middle, carina quite prominent on 

 the anterior half of the volution and becoming nearly obsolete, before 

 reaching the spiral turns ; umbilicus deep, exhibiting the inner volu- 

 tions, broad, nearly as wide as the diameter of the last volution at 

 aperture; suture distinct. 



The only example we have found of this species is a cast, which, 

 on the anterior portion of the last volution, exhibits traces of fine 

 revolving striae. 



Diameter at base, 2^ inches ; spiral angle, 102°. Austin Limestone 

 near city of Austin. 



Genus Anisomyon, Meek and Hayden. 



A. Haydeni, (n. sp.) Shell patelliform, very thin ; length greater 

 than the width ; apex situated nearer the posterior margin, curved 

 slightly forward ; base oval ; anterior side forming a gently convex 

 curve from apex to front margin ; posterior side nearly straight, 

 forming, with the anterior side, an angle of about 115° ; sides nearly 

 flat, sloping at an angle of 94°. Surface marked with fine, concentric 

 lines of growth, and some indications of obscure concentric folds. 



Length, 13 lines; width, 11 hues; height, 6 lines. 



Nearly related to A. patelUformis^ Meek and Hayden, but is not so 

 elevated and the apex is nearer the centre. 



Several species of this gQnus have been discovered by Messrs. Meek 

 and Hayden in the Cretaceous strata of Nebraska, but this is the 

 only species hitherto observed in southern localities. 



Chatfield Point, Navarro County. 



Dedicated to Dr. F. W. Hayden, one of the founders of the genus. 



Collected l)y Dr. (x. (j. Shumard. 



