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Show 452 PROF. W. H. FLOWER ON THE CRANIAL AND | May 1 6, individual peculiarity due to age, it is an important character. A specimen in the Brussels Museum is in an exactly similar condition. On comparing these skulls, can any character be found to indicate that they belong to more than one species ? Of seven of them I have little hesitation in saying that the differences of proportion and general configuration which occur among them may well be considered within the limits of individual variation ; but of one, that from Pegu, in the British Museum, No. 14(>1 a, I am doubtful. There are differences in the conformation of the base of the skull, and in the greater length and more compressed form of the postglenoid process, which separate it from the others ; but without further evidence of correlated differences in other parts of the organization, or without further specimens showing the same characters, I should not feel justified in considering these differences specific, knowing that the development of processes for the attachment of muscles are among the most variable of characters. I merely indicate them to direct the attention of any one who may have an opportunity of examining the skull of R. lasiotis, or of any fresh examples brought to this country, to compare them with this specimen, especially as Pegu is the most northern locality (and therefore nearest to Chittagong) of any of the skulls of this form of Rhinoceros. The three Sumatran specimens from Sir Stamford Raffles all differ somewhat in size and form ; but, allowing for age, the Malacca specimen at the British Museum (R. niger, Gray) does not appear to differ materially from them. Of African rhinoceroses, the British Museum possesses a fine series of eleven skulls, and the College of Surgeons five. The two distinct types, exemplified by JB. simus, Burchell, and R. bicornis, Linn., are recognizable at a glance. The larger size of the former, together v-ith the depressed, spatulated form of the front end of the mandible, distinguish it at once. It is worthy of note that though the front of the jaws, especially the mandible, of the latter, are so much more reduced and narrow, the incisor teeth are better developed and more persistent. In a young Tt. bicornis, from Abyssinia, in which all tbe milk-molars are in place and worn, there are rudimentary incisors (-}-) in both jaws * ; but in two specimens of It. simus of younger age, in which the milk-molars are quite unworn, and the last still concealed in its alveolus, there is no trace of incisors ; so that, as far as this character is concerned, R. simus is that precisely the same circumstance was recorded, though very briefly, in a description of the viscera of a rhinoceros sent from Sumatra by Sir S. Raffles, of which Sir E. Home says (Philosophical Transactions, 1821, parti, p. 271), "the small intestines measured fifty-four feet six inches; the valvular conni-ventes are continued nearly through the whole extent, and in general circular, although not all so." * In a specimen in the Museum of the College of Surgeons, figured in Owen's ' Odontography.' there are two incisors on each side in the mandible ; and these sometimes persist to adult age, as shown by Dr. Gray, P. Z. S. 1869. p. 225. This distinction between li. simus and R. bicornis was also noticed by Duvernoy in the young specimens in the Paris Museum. |