1008 DR. J. E. GRAY ON THE RHINOCEROTID^. [DeC. 12, 



to have belonged to a male. The size and form of the cavity is, no 

 doubt, greatly influenced by the age of the animal. The masseter 

 muscle becomes thicker and shorter as the animal increases in age, 

 the transverse width of the skull under the muscles becoming less as 

 the animal becomes more aged (see some measurements, showing the 

 fact, under R.javanicus). The same is shown to be the case in the 

 series of skulls of li. tmicornis. 



Mr. Edward Blyth has published a memoir on the living Asiatic 

 species of Rhinoceros, with figures of some of the skulls in the Mu- 

 seum of the Society, which may be consulted with advantage (see 

 Journal of the Asiatic Society of Bengal, xxxi. 1862, p. 151) ; but 

 unfortunately I have not had the power of comparing the skulls with 

 those in the Loudon collections : — 



Rhinoceros indicus : narrow type of skull, t. 1. f. 1, t. 2. f. 1. 



R. sondaicus : broad type of skull, t. 1. f. 2, t. 2. f. 2, from the 

 Bengal Sundarbans, and Tenasserim ; t. 1. f. 3, t. 2. f. 3, aged, from 

 Java. 



R. sumatrnnus, t. 3. f. 1, 2, male ; t. 3. f. 3, female. 



R. sumatranus, Tavoy, t. 4. f. 1-4. 



The figures are from photographs, and they show the form of the 

 occiput in the three species, confirming the fact that the occiput of 

 the two-horned species is always flat and erect. 



1. Rhinoceros. 



Skin divided into distinct shields by deep folds. Lumbar fold 

 well marked, and extending from the groin to the back. Horn one, 

 short, conical. Upper lip with a central prominence. Skull : — fore- 

 head broad, flat, or only slightly rounded ; the occipital end shelving 

 from the occipital condyle to the occipital crest ; the occipital con- 

 dyles large, oblong, very prominent ; lachrymal bone moderate. 



The skulls of the larger number of species of this genus have the 

 forehead and the upper surface of the nose flattened ; this is seen in 

 the living animal. But one species, of which there is only a single 

 skull of a young animal in the British Museum, has the forehead 

 and nose subcylindrical (that is, high on tlie central line and arched 

 on the sides), as is the case with the Sumatran and the African Rhi- 

 nocerotes. This character, I have no doubt, is equally visible in the 

 living animal. 



A. Forehead and nose behind the horn flat. 



Nose square on the sides above ; nasal short. R. javanicus. 

 Nose shelving on the sides above ; upper jaw 

 slightly contracted before the grinders. 



Nasal broad, elongate R. unicornis. 



Nasal narrow, short R. nasalis. 



Upper jaw much contracted before the 



grinders ; nasal narrow, short R. flower i. 



B. Forehead and nose subcylindrical, shelving on 



the sides above ; nasal elongate R. stenocephulus. 



