New Species of Fossils from the Pennsylvanian 

 and Permian Rocks of Kansas 

 and Oklahoma 



By J. W. Beede, Ph.D. 

 Associate Professor of Geology in Indiana University 



PELECYPODA 



Chaenomya cylindrica n.sp. 



The shell is of medium size, two and a half times as long as high, com- 

 pressed-subcylindrical in form, being thickest below the beaks in the middle 

 of the shell. The beaks are placed a little less than a third the distance from 

 the anterior to the posterior end of the shell. The shell slopes gently forward 

 from the beaks, with a slight keel shown in the cast, rounding below into the 

 sharp elliptical curve of the anterior end, which, in turn, merges with the 

 very gently convex curve of the ventral margin. This margin becomes 

 nearly straight near its union with the nearly vertical truncation of the pos- 

 terior extremity. The posterior end is somewhat convex and unites with 

 the end of the hinge in such a way as to form a V-shaped notch between the 

 valves. The notch formed by the ventral part of the hinge is broader. 

 The shell is most nearly cylindrical just in front of the slightly flaring 

 posterior aperture. The beaks are appressed and strongly incurved, and so 

 proximate (as seen in the cast) as to appear to have been in contact. The 

 hinge, posterior to the beaks, is slightly concave, equaling half the length 

 of the shell, and the cast shows a high ridge ^vith a deep furrow on either side 

 of it which sinks below the level of the side of the valves. There is a very 

 faint and ill-defined depression extending downward and backward from the 

 beaks to the posterior third of the ventral margin. This is just sufficient to 

 straighten the slightly convex margin arid possibly to make it the least bit 

 sinuous in some specimens. The umbonal ridges are rather well defined above, 

 inside of which is a somewhat flattened zone surrounding the escutcheon. 

 It is quite deep just back of the beaks. The posterior aperture is subcircular. 

 The shell does not appear to have been very heavy, and aside from very 

 gentle undulations of growth, the cast shows no sign of surface markings. 



The anterior adductor scars are of average size, situated two-thirds of 

 the distance from the beak to the antero-ventral extremity. They are con- 

 vex in front, and apparently slightly concave behind, and are roughly 

 quadrangular. The pallial line is deeply impressed, strongly crenulated up- 

 ward, as seen on the cast, and is somewhat near the margin of the shell. 

 At its posterior end it is acutely sinuate and from that point to its union 

 with the posterior adductor it is convex forward. The posterior adductors 

 are ovate-subquadrate in outline and situated on the dorsal part of the 



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