1S75.] in Rhinoceros Sondaicus. 11 



In the first mentioned 2 specimen, the septum, commencing from the 

 ethmoid, is ossified for about 3 inches ; it then divides, the lower portion 

 running to within 5| in. of the maxillo-premaxillary articulation and being 

 intimately connected with the vomer, along whose channel it runs, the 

 upper portion forming a fringe about an inch deep along the inner surface 

 of the conjoined nasal bones (to which it is ankylosed) to within 5f in. of 

 their tip (the curved upper walls of the nasal cartilages being also com- 

 pletely ossified and ankylosed to the inner surface of the nasals and 

 maxillaries for the same distance) ; here there is a break and the bone is 

 perfectly smooth for a space of 2 inches, when there commences a diamond 

 shaped roughened surface, which occupies the whole of the remaining 3f in. of 

 the inner side of the nasals, and on this was articulated the ossified ter- 

 mination of the nasal cartilage. This is of subtriangular form and 

 consists of a plate of bone 3-^ in. long, about 1^ deep, and \ thick. Its upper 

 edge is expanded laterally to a width (in its greatest measurement) of 1|- in., 

 and forms a deep sulcus, into which the tip of the nasals and the roughened 

 articular surface of their underside fit. The anterior edge of this bone 

 is slightly in advance of the tip of the nasals and is 1\ in. in advance of the 

 anterior point of the prsemaxillse, between which point and the lower edge 

 of the septal bone there is a distance of one inch. 



I have since seen the skulls of two other specimens shot at the same place, 

 the one an adult and the other a younger $ This structure was present 

 in both. 



As can be seen from the accompanying drawing, it bears a strong resem- 

 blance to the figure given by Prof. Owen (in his Hist, of Brit. Foss. Mamm.) 

 of R. leptorhinm. There is this difference that in It. leptorhinus the 

 ossified terminal portion of the septum is ankylosed to the nasals, whilst 

 in B- Sondaicus it is not. This, however, might take place at a more 

 advanced age, as, in a foot-note to p. 367, he mentions that the bony septum 

 of M. ticorliinus is free until the animal has quite attained maturity. 

 Judging, however, from the old skulls of Sondaicus before mentioned, I should 

 not think that it would do so, or it would still remain in situ in those 

 skulls. Again, Prof. Owen speaks of the edges of the septum of leptorliinus 

 as being complete, whereas in sondaicus they are not. They bear distinct 

 marks of the insertion of the posterior cartilage, thus leading one to think 

 that, even if it did not ankylose to the nasals, it might in a very old ani- 

 mal become a completely ossified septum. 



Prof. Owen also (Anat. of Vertebrates, Vol. Ill, p. 356) regards the cloison 

 in Bh. ticliorinus as indicative of the great development of the horns 

 in that species, but in Rh. sondaicus the horn is small (5 or 6 iuches as a 

 rule and never exceeding a foot or 18 inches) in the male, and what is very 

 peculiar, the female has no horn whatever. I do not know of any other 



