1898.] Osborn, Evolution of the Amblypoda. Part I. 



203 



to the same species as the male skull (Fig. 21) and skeleton, all 

 the characters of this fine type are now available. 



This is the largest Coryphodon but one, and is very abundant 

 in the Middle Wasatch levels, being represented by a magnificent 

 series of skulls and skeletons in our collection. From these the 

 sexual characters are clearly made out. Tlie large male skull is 

 used in the complete mounted skeleton, Fig. \'i> A. The smaller 



--J? 



Fig. 21. Coryphodon testis. Large male, showing rudimentatary parietal horns. Upper 

 canines partly restored. Skull No. 2867, lower jaw, No. 2872. Am. Mus. Coll. 



female type of this species is represented in the skull No. 2963, 

 and jaws (Nos. 2868, 259) in contrast with the powerful male 

 skulls (Nos. 2829, 2867) and jaws (4322). 



Variations in the last lower molar are considerable, from an 

 oblique to a bilobed (No. 259) or less oblique condition of the 

 posterior crest, with all the stages in reduction of the entoconid 2. 

 Exactly similar variations are found in the lower molars of the 

 larger and smaller members of Series II. The development of 

 entoconid 2 also varies in the posterior molars u])on opj^osite 

 sides of the same jaws of several specimens of C. lobatiis. 



The osteological characters have been fully described and fig- 

 ured by the writer (this Bulletin, 1898, pp. 81-91). Full charac- 

 ters of the vertebral column are shown in Fig. 23. 



Certain specimens (skull, No. 2866) of the still larger C. lobatus 

 have been found below it, and the much smaller C. clcp]iantopus 



