222 STUDIES IN THE EVOLUTION OF ANIMALS 



The central portion of these rosettes is a pyramidal hide-knob, 

 composed of smaller sections, and surrounded by the usual ring of 

 small tubercles. Compare these with the Horse rosettes of Fig. 56 (a). 



The similarity of pattern between the hide-knobs of this 

 Rhinoceros and the bone-rosettes of the Glyptodonts and Arma- 

 dillos is astonishing, and leaves little doubt in one's mind that the 

 Indian Rhinoceros, with its scapular and pelvic shields and its 

 hide-armour, comes down to us from some Armadilloid ancestor. 



In the Horse, every trace of plate and tubercle has disappeared, 

 but they have left instead their indelible pigment-pictures in some 

 varieties of the dappled Horse, as shown in Fig. 56 («), {U) and (c). 



We have now to examine a very interesting feature of the R. 

 Sondaicus given in Fig. 79. Its flanks look as if they were cracked 

 into larger plates than those of the rest of the body. They may be 

 in iaxX fusions of a number of the smaller plates — for although the 

 plates of this Rhinoceros are of a bone-like nature, they may be 

 quite capable of fusion as shown in the hide-plate of the Chittagong 

 Rhinoceros (Fig. 8 1 {ej). 



It would at first seem improbable that stiff bone-rosettes are 

 capable of fusing into larger plates ; but we have already seen an 

 approach to fusion of bone-rosettes in the armour of both the 

 Glyptodon and the Leathery Turtle (Figs. 6"] (a) and 68 (a)). 



This cracked appearance of the hide of R. Sondaicus of Fig. 79 

 forcibly recalls, it seems to me, that flank reticulation which is so 

 common a feature in the dappled Horse (see Figs. 34 and 38). And 

 in both animals it may mean the same thing, viz., in the Rhino- 

 ceros the fusion of one or more bone-rosettes, and in the Horse the 

 fusion of one or more picture-rosettes. If this be conceded, we 

 come to the same conclusion which has been reached frequently 

 before, viz., that both the Rhinoceros and the Horse have descended 

 from some Glyptodontoid ancestor. 



