NO. I THE WHITE RHINOCEROS HELLER 59 



PLATE 13 



(About % natural size) 



Illustrating generic characters 



Fig. i. Coclodonta antiqititatis, adult; from the Pleistocene of the Tunguska 



River, Siberia. No. 6053, U. S. National Museum. 



Tips of premaxilke and nasals broadly united into a solid bridge ; 



teeth with central fossettes of enamel filled by cement; vomer 



thickened. 

 Fig. 2. Ceratotherium sitnum cottoni, female, old; from Rhino Camp, Lado 



Enclave; weathered skull. No. 164597, U. S. National Museum. 

 Teeth with central fossettes of enamel and cement ; three upper 



premolars ; vomer thin and knife like ; occipital crest produced 



beyond condyles. 

 Fig. 3. Diceros bicornis, male, old; Loita Plains, Southern Guaso Nyiro 



District, British East Africa; shot by Col. Theodore Roosevelt, 



June 18, 1909. No. 162930, U. S. National Museum. 



Teeth without fossettes, the folds remaining open ; four upper 



premolars ; sphenoidal process of basi-occipital large. 

 Fig. 4. Rhinoceros unicornis, immature; the milk molars in use; only the first 



molar erupted; permanent incisors just erupting; from the 



menagerie of Barnnm and Bailey ; sex and origin unknown ;. No. 



16251, U. S. National Museum. 

 Teeth with one or two central fossettes, but without the cement 



layer present ; functional incisors present. 



