342 GEOLOGY OF THE BLACK HILLS. 



strong, rounded, and in the older individuals supporting a short spine ; 

 dorsal furrows well pronounced, extending with equal clearness in front of 

 the glabella. Fixed cheeks broad, more than equaling one-half the width 

 of the glabella ; palpebral lobes small and slightly angular, situated oppo- 

 site the middle of the glabella ; ocular ridges distinct, directed anteriorly 

 in passing from the eye to the dorsal furrow. Frontal limb short, not more 

 than one -third as long as the glabella, one-half of its length formed by the 

 strong, rounded marginal rim and furrow. Facial suture directed gently 

 inward from the front of the eye lobe to the anterior margin, with but little 

 curvature ; behind the eye it is directed backward and outward at an angle 

 of from 35° to 40° with the occipital line of the head, with a slightly 

 sigmoidal curvature, giving an elongate triangular form to the postero- 

 lateral limbs. 



There is considerable variation in the form and proportions of the 

 glabella among the different individuals in the collection, the larger speci- 

 mens being proportionally broader and the lateral furrows much more 

 distinctly marked. On the smaller one figured the furrows are not distinct 

 enough to indicate without exaggeration. The presence or absence of an 

 occipital spine is also noticed, dependent apparently on the same cause. 

 It is possible that the two individuals may belong to different species, but 

 from their great similarity in other respects we feel confident that this is 

 not the case. 



This species resemble in some of its characters C. (Bathyurus ?) angulatus 

 H. and W., from the same formation on the west side of Pogonip Mountain, 

 White Pine, Nevada, described in the Geological Exploraton of the Fortieth 

 Parallel, vol iv, p. 220, Plate 2, Fig. 28, but lacks the angular frontal limb of 

 that species, and the facial sutures converge in front of the eye, while in that 

 one they are slightly divergent. We know of no other species with which 

 it is closely related, unless it should prove to be more nearly related to 

 Agraulus Oiveni M. & H., Paleontology of the Upper Missouri, p. 9, Figs. 

 A, B, C, than we are inclined to believe; there are several particulars in 

 which it differs very materially from their figures and also from the descrip- 

 tion given, that would at once mark it as distinct, if it were not that the 

 imperfect material in both cases tend to lead to error. The difference in 



