22 



body of the shell, and rounding gradually in on each side to meet it. 

 A narrow carina runs along the back of the shell, which is quite dis- 

 tinct at the front, but farther back it is hardly perceptible ; front 

 margin emarginate, and the fine striaj of growth, which are more or less 

 visible on the front of the shell, bend gently back to meet the carina. 

 A few very faint longitudinal ridges are observed on each side of the 

 back of the shell, running out upon the expanded disc. 



This species bears a close resemblance to B. patulus Hall, of the 

 Hamilton group of New York, but it diifers in the deeper umbilicus, 

 the general outline of the margin, and its strong carina. 



Locality and position, in the Chemung beds, at Bui-lington, Iowa. 



Genus Euomphalus Sowerby. 



EuoMPHALUS KOBERTi * (n. s.) Shell discoid, of moderate size ; 

 volutions three or more, which gradually enlarge from the apex ; aperture 

 subovoid, or subcircular, its diameter twice that of the adjacent whorl 

 at that point ; umbilicus shallow ; spire umbilicate ; a strong carina 

 running along the upper side of the shell, from which it is regularly 

 rounded on the outer and under sides of the adjacent whorl in the 

 umbilicus. Inside sloping with a slight concavo-convex curve from 

 the carina to the adjacent whorl in the spiral depression. Surface 

 marked by the usual lines of growth. 



This species closely resembles E. pentangulatus Sowerby, the type 

 of the genus, but differs in the less angular outline of the aperture, the 

 greater depression of the spire, and the more rapid increase in the size 

 of the volutions. 



Locality and position, in the upper division of the Burlington Lime- 

 stone, Burlington, Iowa. 



Pteropoda. 

 Genus Conularia Miller. 



CoNULARiA BYBLis (n. s.) Shell large, in the shape of a truncated 

 pyramid, length twice ? the width of the base ; apex broadly-rounded, 

 smooth, sides depressed, convex ; grooves at the angles narrow ; a faint 

 longitudinal depression along the middle of each side ; transverse ridges 

 narrow, distinctly raised, forty-five or fifty to the inch, but slightly 

 curved in passing from the salient angles to the faint central depres- 

 sion, at which they meet with an obtuse angle and cross with slight 

 interruption ; sometimes, however, they alternate for a short distance, 

 and then cross continuously as before. Spaces between the ridges 

 finely crenulate. 



Locality and position, in the Chemung beds at Burlington, Iowa. 



Conularia victa (n. s.) Shell of moderate size, gradually sloping 

 * Prof. Jos. T. Kobert, Burlington University, Burlington, Iowa. 



