134 University Geological Survey of Kansas, 



umbo, not projecting very sensibly above the hinge. The striae 

 are more regular and much fainter, and either very indistinct 

 or absent on at least the upper third of the shell. Both concen- 

 tric wrinkles and lamellae of growth are distinct. Length, 48 

 mm. ; convexity, 18 mm. ; height, 42 mm. ; length of hinge 

 about 28 mm. 



Range and distribution: Upper Coal Measures; Turner. 



This species differs from P. hawni in being very arcuate, hav- 

 ing a plain umbo, and full anterior and posterior marginal 

 outlines, and fine, even striae on the margins. It differs from 

 P. kansasensis in its broad, smooth umbo and indistinct beak, 

 long hinge, and more circular outline. 



Pseudomonotis hawni equistriata. Plate XIV, figs. 3-3b. 



Pseudomonotis hawni equi striata Beede, Kans. Univ. Quart., O. 82. pi. 

 xvin, ff. 3-3b, (1899). 



Shell of medium size, ovate in outline, moderately to quite 

 gibbous, a little oblique with respect to the hinge ; beak moder- 

 ately prominent, extending to or a little beyond the hinge, which 

 is about half the length of the shell and somewhat arcuate. 

 Umbo quite gibbous. Posterior ear very slightly developed, 

 merging into and forming a slight sinus in the posterior mar- 

 gin ; ventral, antero- and postero-ventral margins regularly 

 rounded ; anterior margin sinuate in the upper portion on ac- 

 count of the anterior ear, which is small and round. The sur- 

 face is marked by fine, somewhat regular, rather wavy striae, 

 which increase by intercalation, each fourth to tenth being 

 usually a little larger than the remainder, though not very con- 

 spicuously so. Small lamellae of growth sometimes distinguish- 

 able. Some of the striae extend nearly to the beak. The right 

 valve is flat, or a little concave ; otherwise unknown. Measure- 

 ments, two specimens: Height, 31 mm., 34 mm.; length, 24 

 mm., 26 mm. ; convexity, 7 mm., 13 mm. ; length of hinge, 12 

 mm., 16 mm. These two specimens represent the extremes of 

 convexity. 



Range and distribution : Upper Coal Measures ; Turner. 



This variety differs from P. haivni in being a shorter shell and 



