272 KA.NSA.S UNIVERSITY SCIENCE BULLETIN. 



little like C. woodwardi Reed, but the ribs on the latter species give 

 it an entirely different appearance. The lobes on the anterior part of 

 the carapace are quite different in number and character. 



Cyclus permarginatus, n. sp. Plate XIV, fig. 3. 



Carapace rather flat, disk-shaped, subcircular in outline, with a 

 wide margin. A faint, interrupted median ridge extends along in a 

 shallow furrow from the posterior border to a point near the center 

 of the carapace. At the latter point the furrow divides dichotomously 

 and the branches proceed in an antero-lateral direction, the whole 

 forming an indistinct, Y-shaped depression. On each side of the 

 median ridge or furrow are situated six or seven ribs reaching to the 

 margin. The posterior ribs have an oblique direction, and are more 

 prominent than the anterior ones, which can scarcely be recognized 

 except near the border. 



The anterior surface of the carapace bears several slight elevations, 

 but nothing definite concerning them can be made out. A wide, flat, 

 smooth margin extends around the lateral and posterior borders. The 

 anterior border is hidden by the matrix. Only small portions of the 

 outside surface remain. It is apparently occupied by small pits. 



Measurements : Length, 7 mm. + ; width, 8 mm.-, height, 1.5 mm.; 

 width of margin, 1 mm. 



Position and locality : Upper Coal Measures, Iola limestone, Kan- 

 sas City, Mo. Two specimens. 



The margin of this species is relatively wider than that of any 

 other described species of the genus. It is more like C americanus 

 Packard than any of the other species herein described, but that 

 species is larger, its margin is narrower, and it is apparently not 

 ribbed. 



The radiating ribs give our species an appearance somewhat like 

 that of C. radialis Phillips, but it is flatter than that species, and its 

 ribs are not nearly so prominent. There is no flattened margin in C. 

 radialis. C. permarginatus bears some resemblance to a specimen 

 from Ayrshire, figured by Woodward* and referred by him to C. radi- 

 alis. He states that the specimen is imperfect around the border. 

 If we add a border of one millimeter, the measurements will be quite 

 near those of our species, but as no profile view is given its height 

 cannot be judged. At any rate, our species is not C. radialis. 



C. harknessi H. Woodw. and C. woodwardi Reed are also ribbed, 

 but the prominent lobes on those species give them an aspect entirely 

 different from that of our species. Moreover, they are quite gibbous. 

 There is also some resemblance to C. johnsoni H. Woodw., but there 



*Geol. Mag., pi. XV, fig. 2 (opposite p. 530), 1894. Measurements: Length, 6mm.; breadth, 

 5 mm. 



