PACHYDERMATA. 



875 



maxillary bone in front of the zygomatic pro- 

 cess : these muscles are partially united, but 

 their tendons run separately to be inserted, one 

 into the side, the other into the base of the 

 snout. The fourth pair is comparatively of 

 small size, arising from the nasal bone, and 

 running obliquely beneath the tendons of the 

 two last, terminates near their insertion. The 

 snout and all the above longitudinal muscles 

 are moreover enclosed by a layer of annular 

 fibres, which are a continuation of the orbicularis 

 oris, so that considerable mobility in any 

 required direction is thus amply provided for. 



In the construction of the snout of the Tapir 

 the arrangement of the nasal cartilages and 

 muscles of the nose is still more elaborate, 

 forming a rudimentary proboscis which is only 

 surpassed in complexity by the trunk of the 

 Elephant, the only existing type of the true 

 Proboscidian Mammalia: in fact it is con- 

 structed upon the same principles, the great 

 difference consisting in the diminutive size of 

 the organ in the Tapir when contrasted with 

 the prodigious dimensions of the corresponding 

 parts in the Elephant's proboscis. The nose of 

 the Tapir is composed of two membranous tubes, 

 amply provided with mucous lacuna?, and en- 

 closed in a fleshy mass surrounded by the skin, 

 which consists of longitudinal muscles that take 

 their origin beneath the lower margin of the orbit, 

 and of fasciculi of transverse fibres passing be- 

 tween the skin and the external surface of the 

 membranous nasal tubes. There is a pair of 

 muscles in every way similar to the elevators of 

 the upper lip of the Horse, derived from the pre- 

 cincts of the orbit, and uniting into a common 

 tendon to be inserted into the upper aspect of 

 the nose, a pair of depressors arising from the 

 intermaxillary bones, and also a slip derived 

 from the occipito-frontalis, which is implanted 

 by the intervention of a tendon into the base of 

 the proboscis. 



The proboscis of the Elephant, the only 

 existing example of a completely developed 

 nasal apparatus, forms an elongated cone of 

 four or five feet in length, and gradually taper- 

 ing from the root towards the point, which is 

 terminated by a kind of thumb-like appendage 

 which is endowed with exquisite sensibility, so 

 as to be useful in picking up the smallest 

 objects. Internally the Elephant's trunk is 

 perforated by a double tube, formed by a 

 strong tendinous membrane, through which in- 

 numerable mucous crypts pour fluid abundantly 

 into the nose. The membranous tubes are 

 continued upwards as far as the bony nostrils, 

 but, a little before their junction with the latter, 

 they form two curves, the nasal passages being 

 closed at this point by a cartilaginous elastic 

 valve, which may be opened at the will of the 

 animal, but closes by its own elasticity when 

 the muscles which open it cease to act. 



All the interval between the membranous 

 tubes which follow the axis of the proboscis, 

 and the skin by which it is invested externally, 

 is filled up with a thick layer of muscular 

 substance composed of two sets of fibres. Of 

 these one set passes from the exterior of the 

 membranous tubes to a strong tendinous mem- 



brane situated immediately beneath the skin in 

 such a way that on making a transverse section 

 of the trunk, these muscles represent the radii 

 of a circle : their action will be, of course, to 

 approximate the membranous tubes and the 

 external integument of the trunk, and thus by 

 compressing the intervening space, their con- 

 traction will have the effect of elongating the 

 whole proboscis, without at the same time 

 diminishing the calibre of the membranous 

 tubes, as would have been the case had annular 

 fibres been employed instead of this remarkable 

 arrangement. 



The other muscles of the proboscis are disposed 

 longitudinally, and form a multitude of fasci- 

 culi, disposed in short curves in such a manner 

 that the two extremities of each fasciculus are 

 implanted into the membranous tubes, while 

 the convexity of the arch is adherent to the 

 external tendinous membrane. These fasciculi 

 surround the whole trunk, and extend along 

 its entire length ; their effect being to shorten 

 it from end to end or in any part the animal 

 may please. It is evident that by these partial 

 elongations or shortenings of one side or the 

 other, the Elephant can bend its trunk in any 

 direction with the utmost ease, and make use 

 of it as efficiently as a hand in the performance 

 of many important offices. In addition to the 

 above account of the anatomy of this remark- 

 able apparatus given by the Parisian Acade- 

 micians, Cuvier ascertained that all the longitu- 

 dinal fasciculi which enter into the composition 

 of the trunk are derivations from four great 

 muscles, which, though almost blended together 

 in the trunk itself, are distinct enough near 

 their commencements. Of these the two ante- 

 rior arise from the whole breadth of the frontal 

 bone above the ossa nasi, while the two lateral 

 muscles take their origins from the superior 

 maxillary bones beneath and in front of the 

 orbit. The posterior or inferior aspect of the 

 Elephant's proboscis is covered with fibres, 

 which seem to be continuations of the orbicu- 

 laris oris, and which run obliquely downwards 

 and inwards so as to meet their fellows from 

 the opposite side at an acute angle. With 

 such a structure it is evident that the nasal 

 prolongation of the Proboscidian Pachyderms 

 is able to move in every needful direction, and 

 perform all the duties of a lithe and flexible arm, 

 strong enough to tear the branches from the 

 trees, and sufficiently manageable to be avail- 

 able for the most delicate manipulations. 



The instruments of the senses present few 

 peculiarities. 



In connection with the organs of smell we 

 may conveniently mention the sinuses which 

 communicate with the nasal cavities, which in 

 many Pachydermata are extremely developed. 

 The frontal sinuses of the Elephant are of 

 enormous extent, reaching throughout all the 

 thickness of the frontal, of the parietal, of the 

 temporal, and even extending into the condyles 

 of the occiput. The whole of this extensive 

 cavity is divided into cells by numerous imper- 

 fect septa, irregularly disposed. In the Hog 

 tribes they are equally extensive, but far more 

 shallow; they reach as far back as the occiput, 



