454 PROF. W. H. FLOAVER ON THE CRANIAL AND [May 16, 



am by no means disposed to underrate the testimony of many 

 experienced field-naturalists on this subject. Such osteological 

 evidence as we have upon the question, if applied to the genus 

 JEquus, would probably fail to distinguish the three well-recognized 

 South-African species of Zebras. 



The results derived from the examination of these fifty-four 

 skulls of Rhinoceros may be thus tabulated : — 



A. The adults with a single large compressed incisor above on 

 each side, and occasionally a small lateral one ; below, a very small 

 median, and a very large, procumbent, pointed lateral incisor. The 

 post-glenoid and post-tympanic processes of the squamosal united 

 below the external meatus auditorius. The posterior occipital sur- 

 face sloping from below upwards and forwards, the crest being 

 anterior in position to the condyles. Nasal bones pointed in front. 

 A single nasal horn. Skin very thick, raised into strong, definitely 

 arranged ridges or folds. Rhinoceros, Linn. 



a. Larger size. Upper molar teeth with crochet and crista 

 generally united, cutting off an " accessory " valley from the median 

 sinus. Posterior end of vomer thickened and adherent. Meso- 

 pterygoid fossa and basi-occipital narrow. Hinder margin of palate 

 regularly concave. Occipital surface high and narrow. Ramus of 

 mandible high. 



1. R. unicornis, Linn.* 



R. indicus, Cuv. (R. A. 1817). 



R. stenocephalia, Gray (P. Z. S. 18G7). 



b. Smaller size. Upper molar teeth without crista. Posterior 

 end of vomer thin and free. Mesopterygoid fossa and basi-occipit;d 

 broad. Hinder margin of the palate produced in the middle. Oc- 

 cipital surface broad and low. Ramus of mandible low f. 



2. R. sondaicus, Cuv. (in Desm. Mamm. 1822). 



R. javanicus, F. Cuv. &■ Geoffr. fMammiferes, 1824). 

 R.floweri, Gray (P. Z. S. 1867).' 

 R. nasalis, Gray (P. Z. S. 1867). 



B. The adults with a single moderate-sized compressed incisor 

 above, and a single, laterally placed, pointed, procumbent incisor be- 

 low, which is sometimes lost in old animals. The post-glenoid and 

 post-tympanic processes of the squamosal not meeting below the 

 meatus auditorius. Occipital crest produced backwards so as to 



* Cuvier's names for this and the common African species are often preferred 

 on the following grounds: — "The names of B. unicornis and bicornis, Linn., 

 can be no longer retained, since more than one species is known, both of those 

 with one and of those with two horns " (Van der Hoeven's Handbook of Zoology). 

 But as a precisely similar objection can be raised against the names indicus and 

 africanus, nothing is gained by the change. 



t The differences in external appearance, and especially in the skin-folds, 

 between li. unicornis and R. sondaicus are well seen in the figure published in 

 the Society's ' Proceedings,' 1874, pi. sxviii. ; also in two sketches in ' Nature, ' 

 April 9th, 1871, from the animals living in the Society's menagerie. 



