ORDER PACHYDERM ATA. 421 



are separate, they produce hairs. When they are confluent 

 and in a line, they produce the nails, the claws, and the 

 hoofs, the fibrous appearance of which naturally leads to 

 the supposition of their being confluent hairs; and the 

 same may be said of the scales of the Manis. 



" The quills of the Porcupine, Hedgehog, and other ani- 

 mals, may be regarded as hairs of extraordinary size. 

 When the pores are confluent and in a ring, they furnish 

 the corneous case of the horns of animals of the ruminating 

 class ; and when confluent on a circular area, they supply 

 matter for the formation of a solid horn, such as we see on 

 the Rhinoceros. An examination of the structure and ap- 

 pearance of this latter will be found to support my explana- 

 tion of its nature; as about its base, it is in many instances 

 evidently rough and fibrous like a worn-out brush. It 

 grows from the skin only, in the same manner as the hair, 

 a circumstance which entirely divests of improbability the 

 assertion of its being sometimes seen loose, although by no 

 means so loose as some writers have supposed. Nor is it 

 at all extraordinary that the Rhinoceros should possess the 

 power of moving it, to a certain degree, since the Hog, 

 to which, in a natural arrangement it so closely approaches, 

 has a much greater power of moving its bristles, which, if 

 concreted, would form a horn of the same nature. With 

 respect to the idea which I had entertained, of a single 

 horn being an anomaly, it arose from the consideration 

 that all the osseous parts of animals, excepting the spine, 

 were in pairs ; those which appear single being in fact 

 divided longitudinally by a suture : so that any bony process, 

 such as that which supports the corneous case of horned 

 animals, must, to be single or in the central line of the 

 face or head, stand oyer a suture ; a case which no anato- 

 mist has hitherto discovered in nature. The single horn of 

 the Rhinoceros is therefore no anomaly, because having no 

 connexion with, or not deriving its origin from the bones, 



