ROGERS : SOME NEW AMERICAN SPECIES OF CYCLUS. 273 



are no ribs, and the margin is not as wide as it is in our species. Be- 

 sides, in our species the margin is not separated from the body of the 

 carapace by a furrow. 



Cyclus limbatus, n. sp. Plate XIV, fig. 4. 



Carapace flat, disk-shaped, short transversely elliptical in outline. 

 Margin quite narrow, with a fringe of slender spines which vary in 

 size and length. About twelve can be counted on one side of the 

 carapace, but this does not include the anterior border which is par- 

 tially embedded in the matrix. The spines are flat and pointed at the 

 end. The largest and longest one occurs at the middle of the lateral 

 border. There is a slight posterior median projection of the carapace, 

 and from the appearance it seems that a spine was broken off here. 

 If such be the case we have here in Cyclus the embryotype of Limu- 

 lus, suggestions of some of the characters of the latter genus, namely, 

 the telson and the genal spines. 



The ornamentation of the carapace consists of a series of small, in- 

 conspicuous nodes surrounding the postero-lateral borders. Centrad 

 of these is another row, made up of ill-defined elongate nodes slightly 

 larger than the last- mentioned ones. Next is a pair of low ridges or 

 a '"fork,'' near the anterior end of each of which is a rather large oval 

 lobe, perhaps the most conspicuous feature of the carapace. At the 

 anterior border, near its middle, there is on each side a smaller lobe, 

 and in the V-shaped space, between these and the fork, are several 

 very inconspicuous elevations. 



Measurements: Length, 3 mm.; width, 3.5 mm.; height, 0.75 mm.; 

 length of longest spine, 0.5 mm. 



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

 sas City. Mo. One specimen. 



This species is unique in the possession of a fringed margin. 



Cyclus minutus, n. sp. Plate XIV, fig. 5. 



Carapace very small, longitudinally elliptical in outline, rather flat, 

 and apparently without a margin. A narrow, rather sharp median 

 ridge extends from the posterior border nearly one-half the length of 

 the carapace. Distad of the anterior part of the median ridge there 

 are on each side two other ridges wider than the median one. There 

 the "inner fork" and the "outer fork" of Reed and their expanded 

 anterior ends are much like those of C. packardi, n. sp., antea ( the 

 description of which see). Partly enclosed by the inner fork and in 

 front of the median ridge are slightly elevated nodes, a posterior 

 median one and two paired anterior ones. Around the anterior border 

 are three inconspicuous nodes smaller than those just mentioned. 

 There is a median anterior one and two paired posterior ones. 



