 Reference Base  Note on a partially ossified nasal septum in Rhinoceros s... |
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Fraser, O.L., 1875. Note on a partially ossified nasal septum in Rhinoceros sondaicus. Journal of the Asiatic Society of Bengal 44 (1): 10-12, pl. 5
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| Location: |
Asia - South Asia - India |
| Subject: |
Morphology |
| Species: |
Javan Rhino |
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IV.-Note on a partially ossified Nasal Septum in Rhinoceros Sondaicus,
By O. L. FRASER.
(Received 1874;-Read March 3rd, 1875.)
(With Plate V.)
Whilst cleaning the skull of a Rhinoceros Sondaicus lately obtained by me in the Sunderbuns, I was much surprised to find a partially ossified septum narium—a structure which I had hitherto looked upon as solely characteristic of the fossil Rhinoceros and for any mention of which in a recent species I have looked in vain ; indeed Cuvier (Oss, foss. Vol. 2, p. 26) distinctly states that no such thing occurs in the recent ones. The specimen in question was a female 5 feet 6 in. high and, though a fully adult one (as the size of a foetus she was carrying proved), from the unworn condition of her teeth she certainly was not old, so that the ossification could not be merely the result of age, as is so very often the case with the cartilages and even the tendons of mammals, birds, &c. On looking at some other skulls, I found in two old specimens (one from Java, and the other the locality of which is unknown) traces of where such a structure might have been but had been destroyed either in cleaning or in some other way. In a third (not so old as the two preceding but still an older one than mine) there is distinct evidence of an exactly similar formation to that I am about to describe, though the anterior bone has been lost and part of the posterior portion broken away; this specimen was also from the Sunderbuns. In some 6 or 7 skulls of R. indicus that I examined there was not the slightest indication of it, the vomer being quite distinct, and there being a roughened articulating surface on the inner side of the nasals.
In the first mentioned female specimen, the septum, commencing from the ethmoid, is ossified for about 3 inches; it then divides, the lower portion running to within 5 ½ 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 53 in. of their tip (the curved upper walls of the nasal cartilages being also completely 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 33 in. of the inner side of the nasals, and on this was articulated the ossified termination of the nasal cartilage. This is of subtriangular form and consists of a plate of bone 33 in. long, about 13, deep, and + thick. Its upper edge is expanded laterally to a width (in its greatest measurement) of 13 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 praemaxillae, 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 resemblance to the figure given by Prof. Owen (in his Hist. of Brit. Foss. Mamm.) of R. leptorhinus. There is this difference that in R. leptorhinus the ossified terminal portion of the septum is ankylosed to the nasals, whilst in R. 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 R. ticorhinus 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 leptorhinus 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 animal become a completely ossified septum. Prof. Owen also (Anat. of Vertebrates, Vol. III, p. 356) regards the cloison in Rh. tichorinus 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 Rhinoceros in which this is the case; as in Rh. indicus, as well as the doublehorned species with which I am acquainted, the female carries a horn or horns, though they are generally smaller than in the male.
EXPLANATION OF PLATE V.
Fig. 1. Side view of the skull with the terminal ossification (*) in situ.
Fig. 2. Section of the skull showing the posterior ossification (**)
Fig. 3. Inner or under view of the conjoined nasal bones showing (a) the anterior termination of the upper fringe with the ossified nasal cartilages (b. c.) and (d) the roughened articular surface for the terminal bone.
Fig. 4. Front view of the tip of the nasals with the terminal bone in situ.
Fig. 5. Front view of the bone disconnected.
Fig. 6. Upper or articular surface of ditto.
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