GENERA L CHA RA C TERIS TICS 



The Skeleton 



pen sate for the difference between the temperature of winter and summer, many 

 Mammals which inhabit the colder regions of the globe develop a much thicker coat 

 of hair in the former than in the latter season, of which we have an excellent exam- 

 ple in the horse. In some Mammals, such as the hare and cat, the body is covered 

 with only one kind of hair ; but in other cases, as in the fur-seals, there is one kind 

 of long and somewhat coarse hair, which appears at the surface, and another of a 

 softer and finer nature, which forms the thick and warm under-fur. This under- 

 fur is greatly developed in Mammals of all groups inhabiting Tibet, where it is 

 locally known as ' pashm ' ; and it is this pashm of the goat of these regions which 

 affords the materials for the celebrated Kashmir shawls. Curiously enough, too, 

 animals which usually do not develop pashm almost immediately tend to its produc- 

 tion when taken to the Tibetan region, as is notably the case with dogs. I/ess fre- 

 quently the hair of the body takes the form of stiff bristles, as on the pig ; and still 

 more rarely this thickening is carried to such an extent as to produce spines of 

 which we have the best instances in the porcupine and hedgehog, belonging, it 

 should be borne in mind, to distinct orders. 



The solid horns of the rhinoceroses, and the hollow horny sheaths of cattle and 

 antelopes are very similar in their nature to hairs, and may indeed be compared to 

 masses of hair welded together into solid structures. 



Although a fair idea of Mammals as a whole may be gained without 

 investigation into the nature of their soft internal parts, yet any one 

 who desires to obtain any 

 really accurate knowledge of 

 them must make up his mind 

 to acquire at least some slight 

 idea of the general structure 

 of the bony skeleton, and also 

 of the form and nature of the 

 teeth, since these parts are of 

 the highest importance in 

 classification. 



We have already incident- 

 ally mentioned that the skull 

 consists of two portions, the 

 skull proper, which contains the 

 brain, and the lower jaw. It 

 will suffice to mention, in addi- 

 tion, that the hinder part of the 

 skull is known as the occiput, 

 and that on the front surface the pair of bones roofing over the cavity of the nose 

 are known as the nasals, while those behind them, forming the region of the fore- 

 head, are termed frontals. Further, in the upper jaw, the bones, which carry the 

 hinder- or cheek-teeth are known as the maxillae, while those in which the front cut- 

 ting-teeth are implanted are termed the premaxillse. All the other numerous bones 

 of the skull have received distinct names ; but the reader desirous of becoming 



SKELETON OP THE WON. 



sk. skull ; zy. cheek-bone (zygomatic arch); cv. vertebrae of the neck ; d. 

 vertebrae of the back ; /. vertebrae of the loins ; s. sacrum ; cd. vertebrae 

 of the tail; sc, shoulder-blade (scapula); h. arm-bone (humerus); r. u. 

 bones of fore-arm (radius and ulna); cp. wrist (carpus); me. meta- 

 carpus; ph. toe-bones; pv. haunch-bone (pelvis); fm. thigh-bone 

 (femur); p. knee-cap (patella); tb. fb. bones of the lower leg (tibia and 

 fibula); ts. ankle (tarsus); m. metatarsus. 



