PACHYDERMATA. 



859 



degree of developement of the snout of the Pig 

 and the semi-proboscidean nose of the Tapir. 



The following genera of Pachydermatous 

 Quadrupeds have been distinguished by natu- 

 ralists, many of which are still in existence, 

 but the majority are met with only in a fossil 

 state, the names of the latter being printed in 

 italics. 



Fig. 465. 



Hippopotamus 



Toxodon 



Coryphodon 



Acerotherium 



Elasmotherium 



Macrauchenia 



Hexuprotodon 



A n thracotli erium 



Chceropotamus 



Hyracotherium 



Dichobune. 



Elephas, (fig. 464'J 



Mastodon 



Dinotherium 



Tapirus 



Pul&otherium 



Lophiodon 



Hyrax 



Rhinoceros 



Anoplotlierium 



Dicotyles 



Phacochaerus 



Sus 



Osseous system. The skeleton of the Pachy- 

 dermata is generally remarkable for the massive 

 character which is conspicuous in every region, 

 indicative, at a glance, of the ponderous strength 

 and generally inactive habits of the animals 

 belonging to this order; but inasmuch as they 

 are destined to obtain their food under very 

 various circumstances, which demand a cor- 

 responding diversity of structure in different 

 parts of their bony framework, some detail will 

 be necessary in adverting to this part of their 

 economy. 



Cranium. The cranium of the Elephant, the 

 only living genus of Proboscidian Pachyderms, 

 is quite unique in its external configuration, 

 and from its vertical elevation confers a re- 

 markable aspect of sagacity to the animal ; its 

 intelligence, however, although really surpri- 

 sing when contrasted with the stupidity of 

 other genera belonging to this class of quadru- 

 peds, has doubtless been much exaggerated in 

 consequence of its imposing appearance. This 

 peculiar contour of the skull depends upon 

 several circumstances having nothing whatever 

 to do with cerebral developement, but being 

 entirely dependent upon mechanical arrange- 

 ments required to support the enormous tusks 

 that project from the upper jaw, and to give 

 origin to the muscles of the proboscis, a nasal 

 apparatus here only met with in a state of 

 complete developement. The extreme short- 

 ness of the bones of the nose, the nearly vertical 

 position of the upper maxilla and ossa incisiva, 

 and the swollen vault of the forehead produced 

 by an excessive enlargement of the frontal 

 sinuses, (Jig. 466,J which gives extent of sur- 

 face to the exterior of the skull, all concur to 

 mask the real condition of the cranial cavity, 

 which, as is easily seen in the next figure, 

 (Jig. 465,) occupies but a very small portion of 

 the posterior and central portion of this gigantic 

 cranium. 



The general character of the individual bones 

 of the cranium and their modifications in the 

 principal Pachydermatous races will be under- 

 stood from the appended figures better than 

 from any lengthened description. 



The occipital bone is very extensive, forming 

 by itself the entire posterior wall of the cranial 



Skull of young Indian Elephant. 

 a, intermaxillary bone ; b, nasal bone ; c, superior 

 maxillary; d, jugal; /, frontal; g, parietal; 

 h, temporal ; i, inferior maxilla. 



cavity, and even in the Elephant advancing 

 considerably upon its upper surface, where at an 

 early period it becomes so firmly consolidated 

 with the parietals, and these again with the fron- 

 tals and temporals, that the whole roof of the skull 

 appears to be formed of one bone. In the hog 

 tribe, the Hippopotamus and the Tapir, it termi- 

 nates superiorly in an abrupt and broadly ex- 

 panded crest, into which the muscles of the neck 

 are inserted ; and not unfrequently the deep fossae 

 and prominent ridges visible upon its posterior 

 aspect testify to the massive strength required 

 in this part of the muscular system, either to 



Fig. 466. 



Vertical section of Elephant's skull, shewing the relative 

 proportions between the cranial cavity and the sinuses 

 of the skull. 



