62 COLOHADU COLLEGE STUDIES. 



the beveled zone between the aperture and the peristoniial 

 ed^e being eontinuous around the aperture, broadest where 

 it rests against the whorl above, narrowest on the basicolu- 

 niellar quarter: inner lip free opposite and below the umbili- 

 cus, adnate above it, the free portion everted so as to encroach 

 slightly upon the umbilicus and to overarch about one-third 

 of it: umbilicus somewhat narrowed, but deep, striated or 

 costellate, each costella terminatir.g interiorly in a slight en- 

 largement, the series of narrow tubercles thus produced giving 

 the angulated border of the umbilicus a creliulated aspect; 

 umbilico-basal angle not extending over the tumid labial 

 region. The fine growth-lines of the shell are directed 

 obliquely liackward from the suture above, on the upper part 

 of the whorls, becoming transverse ou the lower part of the 

 body- whorl. 



Measnremenis. — Height 10.5, breadth 14.5 miu.: diver- 

 gence of slopes 109 degrees. 



Occurrence. — In the Caprina limestone of Travis county, 

 Texas, in the south blutfs of the Colorado river, west of South 

 Austin; associated wnth Requienid patcujiatd, Monopleura 

 marcida, M. pingwiscula, Lucina acide-lineolata, Nerinea 

 pellucida, and other fossils of the Barton creek and Deep 

 Eddy blutf fauna. 



For the type-specimen, I am indebted to Prof. B. S. Brown, 

 after whom the species is named. The si^ecimen, like others 

 of this fauna, is beautifully preserved in calcite, and has a 

 bright red tinge, due to a thin incrustation of iron oxide. 



Neritoma marcouana, sp. nov. 



Shell small, of moderate thickness, depressed-subglobose, 

 oblique, consisting of apparently three and a half whorls; 

 spire sublateral, small, eroded; body- whorl large, ventricose, 

 evenly rounded, nearly smooth, its upper part with feebly 

 elevated costelUe, extemling obliquely upward (that is, toward 

 the suture and at the same time somewhat toward the aper- 

 ture), and separated by round-bottomed, groove-like intervals 

 of about the same ])readtli, that begin, in part abruptly, at or 

 just above the periphery; periphery and base of body-whorl 



