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Show 516 ON A NEW FORM OF AFRICAN BHINOCEROS. [June 6, The question is to what species of Rhinoceros these two horns (which I now exhibit) are to be referred. It will be seen that they are remarkable for their length, thinness, and especially for their comparative roundness and their small size at the base. Since the publication of Mr. F. C. Selous's excellent paper on the African Rhinoceroses (P. Z. S. 1871, p. 725), it has been generally agreed by naturalists that there are only two known species of this genus in Africa-the Black Rhinoceros (R. bicornis) and the White Rhinoceros (R. simus). Of the Black Rhinoceros a fiue series of horns has been figured by Mr. Selous (l.s.c), showing the variations that exist in the comparative length of the anterior and posterior horns. The anterior horn of the Black Rhinoceros, though, save in very exceptional cases, always longer than the posterior horn, seldom reaches more than 24 inches in length, though occasionally longer \ On the other hand, the front horn of R. simus grows, as is well known, to an extraordinary length, varying from 18 to 48 inches, and reaching even 57 inches in abnormal specimens. This horn is, however, of great thickness at the base and much more compressed laterally than is the case with the specimens now in question, and in fact of quite a different character. Moreover R. simus, now almost extinct2, has never been known to occur north of the Zambesi. It is not possible, therefore, to refer Mr. Holmwood's specimens to R. simus. There remains the question whether they can belong to abnormal individuals of R. bicornis, to which form of Rhinoceros they would appear from general characters to be most nearly related. Before considering the question I will shortly describe the specimens. a (fig. 1) is 42 inches in length from the base of the thickened pedicel along the curve to the top of the horn. The. pedicel is nearly circular, about 5 inches across on its lower surface. It is rounded, not flattened in front. At about 5| inches from the base the true horn emerges from the pedicel; here it is ovate in shape, about 2*5 from front to back aud 2*1 from side to side. It is nearly straight at the base, but curved gently backwards in the last third of its length. It is very smooth and of a uniform dark brownish black in colour. b (fig. 2) is generally similar, but not quite so long (41 inches), thicker at the base, where the horn emerges from the pedicel, and much more rapidly curved backwards. It is also much paler in colour. On comparing these horns with anterior horns of the Black Rhinoceros (two pairs of which Mr. Selous has kindly lent me for the purpose), it will readily be seen that they are at once recog- 1 There are two horns in the British Museum, referred to this species (1520 and 1520 i), 42 and 40 inches in length respectively. See Hand-1. Edent. p. 52 (1873). 2 A recent letter, addressed to the ' Field' by Mr. Selous (Field, vol. 80, p. 803,Nov. 26th, 1892), shows that the White Rhinoceros still exists in Northern Mashonaland, a herd of six having been met with by Messrs. Eyres and Coryn-don about 100 miles N . W . of Salisbury. |