ELEPHANTID.E MAMMALIA. ELEPHAXTIDJJ. 



181 



FAMILY I. ELEPHANTID^E. 



Excluding the oceanic cetacea, the living represen- 

 tatives of this family are the most bulky of all existing 

 Mammalia. In the miocene and pleistocene deposits 

 of the tertiary epoch, the remains of extinct species are 

 extremely abundant ; some of them such as the mas- 

 todon, Plate 32, fig. 100, and deinotherium being 

 generically distinct. Probably the latter genus should 

 be regarded as the type of a separate family, seeing 

 that the lower jaw is supplied with enormous tusks, in a 

 manner altogether unique ; their crowns being directed 

 downwards and backwards, and the roots inserted 

 into a prolongation of the symphysis or anterior 

 central prominence of the inferior maxillary bone. 

 Whatever differences may have existed in these aber- 

 rant forms, the true elephants are distinguished by the 

 possession of a remarkable nasal appendage or proboscis, 

 commonly called the " trunk." This organ has a taper- 

 ing cornucopial outline ; it is pierced at the tip for the 

 two nostrils, and at the centre of the upper margin is 

 furnished with a finger-like process which, in con- 

 junction with a thumb-like thickening of the inferior 

 border, serves the purpose of a hand. The extra- 

 ordinary prehensile powers of the trunk are familiar 

 to every one ; but when it is considered how readily 

 the same instrument can detach a straw or uproot a 

 tree, our conceptions of its muscular and tactile powers 

 can scarcely be too highly exalted. Another pecu- 

 liarity in the organization of these proboscidean pachy- 

 derms has reference to the bulky aspect of the head. 

 This feature, however, is not due to any increased 

 development of the brain, but simply to a remarkable 

 extension of certain air sinuses in connection with the 

 cranial bones (fig. 69). The vertical elevation of the 

 forehead thus conferred upon the elephant, has led 

 many to ascribe to the animal an almost super-quad- 

 rupedal intelligence ; but if, in this case, their opinions 

 are based upon phrenological considerations, it is 

 our duty to inform such enthusiasts that the frontal 

 prominence and elevation of the cranial vertex bear no 

 relation whatever to the bulk of the brain contained 

 within the comparatively restricted cerebral cavity. 

 That elephants possess considerable sagacity, no one 

 will venture to deny ; but that they display this mental 

 quality in virtue of any corresponding enlargement 

 of the great nervous centre, is utterly inadmissible. 

 Another interesting peculiarity in this family consists 

 in the form and arrangement of the teeth. Ordinarily, 

 it is stated that the dentition comprises two incisors, 

 no canines, and three molars ; but in reality the grinders 

 are more numerous, no less than seven being conse- 

 cutively developed on each side of either jaw. This 

 apparent discrepancy results from the circumstance, 

 that only two molars are present on one side of either 

 jaw at the same time ; but, in the progress of growth 

 and age, those first employed give way to a succession 

 of similar teeth developed from behind. In like manner 

 the two large permanent incisors are preceded by a 

 similar pair, which, however, have never attained full 

 development. Histologically speaking, the tusks con- 

 sist entirely of dentine, which, on transverse section, 



exhibits an elegant series of decussating curvilinear 

 striae. This appearance is peculiar to the ivory of 

 elephants, and considerably enhances its commercial 

 value. In a structural point .of view, the molars are 



\-\K. 60. 



Vertical Section of the Skull of the Elephant 



still more remarkable. If reference be made to Plate 

 32, fig. 102, it will be observed that the grinding surface 

 marked by a number of parallel bars. These consist 

 of alternating plates of the three different substances 

 which ordinarily enter into the composition of the 

 mammalian tooth ; the white bands representing plates 

 of enamel, each inclosing a central lamina of ivory or 

 dentine, whilst the several outer spaces between these 

 formations are filled up with a special osseous devel- 

 opment termed cement. In the African elephant the 

 enamelled plates have a lozenge-shaped outline, as 

 seen in Plate 32, fig. 101 ; in the Siberian mammoth, 

 or Elephas primigenius, they are more numerous and 

 closely approximated ; and in the mastodon are elevated 

 into a series of tuberculated cones. In regard to the 

 skeleton, we may remark the general massiveness of all 

 the bony elements, the twenty pairs of ribs reaching 

 backwards almost to the pelvis, the remarkable breadth 

 of the scapula in proportion to its length, the prodigious 

 development of the external condyle of the humerus, 

 the simple form of the femur, the peculiar articulation 

 of the superior extremity of the radius, and the odd- 

 toed, pentadactylous feet. The digestive organs are 

 extremely bulky as in herbivorous quadrupeds gene- 

 rally. The gall-bladder is complicated by numerous 

 internal septa, and intimately connected with the walls 



