118 Trans. Acad. Sci. of St. Louis. 



end, less rapidly near the small end; surface marked by faint, 

 irregular lines of growth which run obliquely around the 

 shell, and in flattened specimens are more advanced along 

 one edge. Length of largest specimen, 56 mm.; diameter at 

 larger end 5 mm.; at smaller end about 1 mm." 



PTEROPODA. 



CONULARIA BYBLIS White. 



PL VII. f. 7. 



Shell large, elongate pyramidal; the lateral surfaces nearly 

 flat, their margins diverging at an angle of about 15°, marked 

 along the mesial line by a slight depression ; transverse costae 

 somewhat variable in their distances apart, there being from 

 12 to 18 in a distance of 10 mm., each costa forming at the 

 median line of the lateral surface a rounded, obtuse angle of 

 about 120°; the spaces between the costae crenulate. The 

 angles of the shell at the lines of junction between adjacent 

 lateral surfaces are marked by narrow grooves formed by the 

 incurved margins of the sides. The dimensions of the type 

 specimen cannot be accurately determined because of its 

 crushed and distorted condition, its maximum length as pre- 

 served is 76 mm., and its greatest width 54 mm. ; if the sides 

 of the shell be projected to a point its length is nearly twice 

 the present length of the specimen. 



Remarks. The specimen here illustrated is the type. In 

 the figure the transverse costae are made to form too abrupt 

 an angle as they cross the median line of each lateral surface, 

 this angle should be more rounded. One specimen referred 

 to as a variety of this species in the University of Michigan 

 collection, is somewhat larger than the one illustrated although 

 it is much more crushed and distorted. It differs from the 

 type in having the transverse costae somewhat closer together 

 and in having them conspicuously crenulate. There are still 

 other more fragmentary specimens which show various de- 

 grees of crenulation of the costae, and also a considerable 

 variation in the distances separating the costae. It therefore 

 seems, either that this species is a very variable one, or that 

 two or more distinct species of Conularia are present in the 



