U. S. GEOLOGICAL SURVEY 



MONOGRAPH 65 PLATE CVI 



TYPE SKULL, JAW, AND TEETH OF DIPLOCLONUS TYLERI 



After original figures by Prof. R. S. Lull. (See p. 503.) One-sixth natural sise. Amheril College Zool. Coll. 327, 

 type, "near the head of Bear Creek, a tributary of the Cheyenne River [S. Dak.]. The exadt locality -was on 

 the north side of Spring Draw Basin, about 10 miles from the mouth of Bear Creek. Here some 200 feet of titano- 

 there beds were found, lying upon Fort Pierre deposits, in which titanothere bones were discovered from a 

 point 6 feet above the contadt upward; the specimen under consideration lying 35 feet above the base of the beds, 

 hence in the upper part of the lower division."— J. B. Hatcher, Am. Naturaliil, vol. 27, p. 218, 1893, cited by 

 R. S. Lull, 1905, p. 443. This large skull recalls Brontopi robuiius or a progressive B. dispar in general appearance 

 but is referred to the subgenus Diploclonus partly because it has a large accessory hornlet. The canine is very 

 ^out; in p* there is pradlically but one internal cusp, the po^ero-internal cusp being barely defined and con- 

 tinuous with the cingulum. The general pattern of the premolars is the same as in Allops and Brontops. The 

 lower jaw recalls that of Brontops robuflus. (See Pis. XCVn, XCIX, and ClI) 



