MUSEUM OF COMPARATIVE ZOOLOGY. 97 



m. m. 



Spec. s. Diameter fourth premolar, antero-posterior .045 ; transverse . .065 



" " third " " .035 " . . .050 



" " second " " .028 • " . . .032 



" " first " " .017 " . . .017 



" Lower jaw, length, angle to front of canine 470 



" " depth, tip of coronoid to inferior border 295 



Vertebras. 



Spec. h. Atlas, greatest width, .356 m. ; greatest depth 100 



Spec. pp. Axis, greatest width, .18 m. ; length of centrum 090 



" " " depth, spine to base of centrum, estimated . . .140 



Spec. p. Fifth cervical centrum, antero-posterior .074 m., vertical .068 m., 



transverse .076 m. 

 Spec. o. Tweli'th dorsal centrum, antero-posterior .075 m., vertical 

 .055 m., transverse .058 m. 



Appendicular Skeleton. 



Spec. c. Scapula, vertical diameter, approx., .295 m. ; glenoid cavity, ant. 



post 900 



" Humerus, length of, .308 m. ; breadth, head and tuberosity . . .155 



Spec. a. Radius, length, .285 m. ; breadth, proximal, .093 m. ; distal . .098 



" Ulna, greatest length, .36 m. \ sigmoid facet to cuneiform facet .295 



" Carpus, greatest transverse diameter, .130 m. ; ditto vertical . .057 



" Mtc. III., breadth . . .070 m. ; length 116 



" " II. " . . .043 " 100 



" " I. " . . .040 " 092 



Spec. e. Left innominate bone, diameter, antero-posterior 495 



" Length of pubis, .185 m.; of ischium, .20 m.; of ilium . . . .340 

 Spec./. Femur, length of, .46 m. ; diameter, head and great trochanter . .165 



Spec. #. Tibia, length of, .37 m. ; width, proximal 140 



Spec, q and r. Tarsus, tuber calcis to distal facet of mts. III., approx. . .220 



" " transverse diameter 108 



" Second metatarsal, length 088 



Restoration. (See Plate II.) 

 The restoration of Aphelops fossiger confirms Cope's statement that the pro- 

 portions of the animal were rather those of the hippopotamus than the rhi- 

 noceros. The body was long, the chest deep, the limbs and feet short and 

 massive, and supplied with powerful muscles. The skeleton is about 9 feet 

 long and 4 feet 6 inches high. Thus Aphelops presented a wide contrast to its 

 tall, comparatively slender predecessor, Acerathervum^ of the lower Miocene. 

 The increase in brain capacity shows that its nervous organization kept pace 

 with its general muscular and skeletal development. We may infer that the 

 extinction of Aphelops was due to climatic changes, rather than to any defects 

 in its internal organization, because the brain, teeth, and feet are, in themselves, 

 as adaptive as in any of the present persisting types. 



VOL. XX. — NO. 3. 7 



