64 SMITHSONIAN' MISCELLANEOUS COLLECTIONS VOL. 6l 



PLATE 18 

 (About Y% natural size) 



Illustrating subspecific character of greater dorsal elevation of lambdoidal 

 crests in simum than in cottoni, and its variation due to age in the latter race. 

 Fig. i. Ceratotherium simum simum. female, old; from South Africa; exact 

 locality not known ; specimen in the department of paleontology at 

 the American Museum of Natural History. 



Horn attached to boss so that exact depth of dorsal concavity is 

 not obtainable, the marked deflection upward of the lambdoidal 

 crests shows it to be much greater than in cottoni. 

 Fig. 2. Ceratotherium simum cottoni, male, immature ; from Rhino Camp, Lado 

 Enclave ; shot by Kermit Roosevelt, January 13, 1910. No. 164589, 

 U. S. National Museum. 



This skull has greater depth to the dorsal concavity than any 

 other, which character is due chiefly to its extreme immaturity. 

 Fig. 3. Ceratotherium simum cottoni, female, adult; from Rhino Camp, Lado 

 Enclave ; shot by Kermit Roosevelt, January 21, 1910. No. 164594, 

 U. S. National Museum. 



This skull exhibits the least amount of depth to the dorsal con- 

 cavitv. 



