MONOCLONIUS (CENTROSAURUS) CUTLER! 87 



Monoclonius (Centrosaurus) cutleri Brown 10 



Holotype: No. 54 J" A.M.N.H.; posterior half of the skeleton, ami a section of the epidermal impression over- 

 Lying the right lemur. 

 Horizon: Belly River formation. 



Locality: North fork of Sand Creek, 12 miles below Stevcvillc, Red Deer River, Alberta, Canada. 

 Collector: American Museum expedition of 1913. 



A few skeletal comparisons can also be made in the three specimens which are sufficiently com- 

 plete, namely, the types of nasicornus and cutleri, and the Yale specimen of flexus. These contrasts 

 lie in the form of the ilia, ischia, sternal plates, femur-tibia ratio, curvature of the posterior ribs and, 

 in the Yale specimen, the curious backward offsetting of the neural arch and spines of the dorsals as 

 compared with those of nasicornus (see Figs. 9-15). 



Comparing the type specimens of nasicornus and cutleri, the following differences are observed: 

 The preserved vertebrae are a little larger in cutleri, but, according to Brown, of exactly the same 

 form as in nasicornus, no distinctions being seen in any part of the column. The sternal plates of 

 cutleri are markedly longer, narrower proximally, and wider distally than in nasicornus. The 

 anterior blade of the ilium is much longer in cutleri than in nasicornus. The ischium of cutleri is 

 long and comparatively straight, with the distal end sharply decurved and expanded, in contrast to 

 the more even curve throughout in nasicornus. The femora are more than one and one-half times 

 the length of the tibiae in cutleri, and not over one-third longer in nasicornus, the ratios being 1 .60 

 to 1 in the former, 1.32 to 1 in the latter. A final detail is the remarkable curvature of the last 

 dorsal rib through an arc of more than 180° in cutleri and in the Yale specimen, and not at all in 

 nasicornus. 



The skeleton belonging to the Yale specimen, which the skull characters determine to be flexus, 

 is a curious compromise between nasicornus and cutleri. The dorsal vertebrae differ in a marked 

 way from those of nasicornus in the offsetting of the neural arch and spines to the rear, as has been 

 mentioned. In this they disagree with cutleri. The femur-tibia ratio in the Yale specimen, which 

 is as 1.43 to 1, is intermediate between that of nasicornus and cutleri. Unfortunately, the distal 

 half of each ischium has been restored after nasicornus, but the elongation of the ilia is again inter- 

 mediate. And last of all, the two sternal plates, imperfect in outline, resemble in the one cutleri, 

 and in the other nasicornus. These are the distinctive features which characterize the Yale skeleton ; 

 but without the skull, one would hardly be justified in erecting a new species for its inclusion. The 

 feeling is quite strong, however, that were the skull of cutleri known, it would prove to resemble one 

 of those we have included under the species flexus. 



Genus STYRACOSAURUS Lambe 



Styracosaurus albertensis Lambe 20 



PI. VIII 



Holotype: No. 344 G.S.C.; skull without lower jaws. 



Horizon: Belly River formation. 



Locality: \ x / 2 miles south of Denhart Ferry, Red Deer River, Alherta. 



Collector: C. H. Sternberg, 1913. 



Generic characters are as follows: "Skull massive, elongate, pointed in front, and greatly 

 extended behind to form a neck-frill with long, robust, tapering outgrowths projecting obliquely 

 backward and outward from its posterior border. Fontanelles of moderate size within the coalesced 

 parietals. Squamosals somewhat quadrangular and entering largely into the formation of the front 



rown, I!., 1917, pp. 301-306. 

 -" Lambe, L. M., 1913, p. 109. 



