File:Heller, The White Rhinoceros (1913), Pl. 12.jpg

• Fig. I. Rhinoceros unicornis, immature; milk molars in use; permanent incisors just erupting; from the menagerie of Barnum and Bailey; sex and origin unknown. No. 16251, U. S. National Museum.

Dorsal outline deeply concave; incisors in both jaws; post- glenoid and post-tympanic processes united.

• Fig. 2. Diceros bicornis, male, old; Loita Plains, Southern Guaso Njoro District, British East Africa; shot by Col. Theodore Roosevelt, June 18, 1909. No. 162830, U. S. National Museum.

Occipital crests produced above dorsal plane of skull but not beyond the condyles ; post-glenoid and post-tympanic processes separated.

• Fig. 3. Ceratotherium simum cottoni, female, old; from Rhino Camp, Lado Enclave; weathered skull. No. 164597, U. S. National Museum.

Nasals and premaxillse widely separated ; dorsal profile of skull showing very slight deflection of the occipital crests, but the latter greatly produced backward beyond condyles; post-glenoid and post-tympanic processes separated.

• Fig. 4. Coelodonta antiquitatis, adult; from the Pleistocene of the Tunguska River, Siberia. No. 6053, U. S. National Museum.