624 ANATOMY OF VERTEBRATES. 



the gigantic extinct members of the order Bruta (Megatherium, 

 fig. 27 9, e.g.) the claws and their core or supporting bone 

 rivalled the horns of many Ruminants in bulk. 



§ 364. Horns. — The horn of the Rhinoceros consists of a 

 uniform compact agglutinate mass of epidermal fibres, the slightly 

 concave base of which is attached to the dermo-perioste of as 

 slightly elevated a rugous tract of bone : it is medial in position 

 and symmetrical in shape. 



The Asiatic continent and the Island of Java have the one- 

 horned species called Rhinoceros indicus and Rh. sondaicus (vol. ii. 

 p. 284, fig. 165): the same continent and the Island of Sumatra 

 have the two-horned species (Lh. sumatranus): all the known 

 kinds of Rhinoceros, four in number, of Africa are two-horned : 

 in these one horn is behind the other in the same medial tract of 

 the upper part of the skull. 1 The nasal bones support the constant 

 or anterior horn : when a second is superadded it is attached to 

 the frontals, and is, usually, shorter than the first ; 2 in Rhinoceros 

 Oswellii considerably shorter ; but in Rh. Ketloa it is almost or 

 quite as long as the first horn, but is straight. The horn or 

 horns of the female Rhinoceros are usually shorter or smaller than 

 in the male. In the young one-horned Rhinoceros living, from 

 1834 to 1849, at the Zoological Gardens, the new fibres of the 

 growing horn were chieflv added to the front and sides, those at 

 the back decaying, and by this direction of addition the horn pre- 

 served its relative position to the fore part of the growing head. 

 This local decay and renovation became less conspicuous after the 

 animal had gained its full size ; and in the long horns of aged 

 individuals the whole basal circumference presents the same 

 smooth and polished surface, the reception of additional matter 

 being then restricted to the completed area of the base. 



Raise and prolong the bone covered by the vascular horn- 

 forming tegument, and the next type of horn would result. In 

 most Ruminants (Oxen, Antelopes, Goats, Sheep) a pair of pro- 

 cesses extend from the frontal bones, the dermo-perioste of which 

 develops a sheath composed of horny fibres : but the supporting 

 process is long and conical, and the horn which sheaths it is corre- 

 spondingly hollow, whence the Ruminants, so armed, are termed 

 6 hollow-horned.' The bone is termed the ' core : ' it has usually 

 a rugous or grooved exterior : in Bovidce and Ovidce the frontal 



1 The nasals of the fossil Rhinoceros minntus, Cuv., show a transverse pair of small 

 and smooth conical processes, which cannot confidently be inferred to have sustained 

 horns : like the Rhinoceros incisions, I believe it to have been hornless. 



2 There are reports, needing confirmation, of a small third horn, as a rare variety. 



