532 



RUMINANTIA. 



to give full effect to such an arrangement, 

 many species are provided with a special 

 glandular sebaceous follicle between the toes, 

 whose office is to furnish a lubricating secre- 

 tion, calculated to prevent injury from friction 

 of the digits one against the other. Fig. 354*. 

 represents the position and dimensions of this 

 organ in the Sheep. According to Sir Charles 

 Bell there is yet another intention in this cloven 

 form, viz., that of aiding the voluntary eleva- 

 tion of the foot when it has sunk deeply into 

 soft ground. " We may observe," he says, 

 " how much more easily the Cow withdraws 

 her foot from the yielding margin of a river, 

 than the Horse. The round and concave form 

 of the Horse's foot is attended with a vacuum 

 or suction as it is withdrawn ; while the split 

 and conical shaped hoof expands in sinking, 

 and is easily extricated."* 



DIGESTIVE SYSTEM. Buccal Cavity. 

 The lining mucous membrane of the oral 

 cavity is very rough, being covered throughout 

 with very prominent papillae. At the roof of 

 the mouth they have a flattened form, and are 

 arranged in parallel rows, producing a series of 

 ridges or bars, the margins of which are den- 

 ticulated and directed backward. They are 

 very conspicuous in the Camel, and in the 

 Giraffe we have counted from fourteen to 

 eighteen rows ; the papillae of the anterior 

 ridges, however, lose much of their linear 

 arrangement. Respecting the use of this pe- 

 culiar grooved structure, Mr. John Zaglas 

 appears to have offered a satisfactory solu- 

 ion. Speaking of the action of the tongue 

 during deglutition, he says, " I may here 

 hazard the opinion, that the transverse rugag 

 on the palate of Man and the lower animals 

 are intended, to a certain extent, for the sup- 

 port of the tongue in the act of elongating 

 itself backwards. The varieties which they 

 exhibit coincide with what would appear to 

 be required in the relations of the tongue and 

 oral cavity. In Man, in whom the alveolar 

 process is perpendicular, they are slightly de- 

 veloped, and situated far forward. In the 

 lower animals, in which the alveolar process 

 is small or oblique, the rugae are situated 

 farther back, and are more full}' marked, par- 

 ticularly in those which swallow bulky arid 

 comparatively rough morsels, as in the ru- 

 minants and solipeds." f The oral roof of the 

 Giraffe is marked by an extensive deposit of 

 leaden-coloured pigment, stretching from the 

 alveolar margin to the centre of the palate ; 

 small isolated patches also occurring still far- 

 ther back. A callous thickening of the gum 

 occupies the place and supersedes the function 

 of the non-developed intermaxillary incisives. 

 The buccal papilla? attain their greatest size in 

 the region of the cheek opposite the true mo- 

 lars. In this position they take on the cha- 

 racter of horny spines, very like those seen in 

 the oesophagus of the Turtle. They have 

 either the form of simple elongated cones, or 

 are aggregated together, and blended so as to 



* Bridgewater Treatise, p. 92. 



f Goodsir's Annals of Anatomy and Physiology, 

 Part II. p. 122. 



present two, three, or even four points. This 

 complicated disposition is well shown in the ac- 

 companying figure (fig. 355.)from the Camel ; in 



Fig. 355. 



Buccal papillce of the Bactrian Camel, (From F. 

 Miiller and Wedl.) 



the Giraffe the longest spines, which are fully half 

 an inch in length, give off secondary processes, 

 thus resembling very closely the fungiform pa- 

 pillae of the human tongue after the epithelial 

 layer has been removed. Professor Owen is 

 of opinion that the principal function of these 

 organs consists in adjusting the bolus during 

 mastication. 



Teeth. Consistent with the compound 

 character of the ruminant stomach, a parallel 

 complexity obtains in the structure of the 

 teeth, at least, in those concerned in tritu- 

 rating the food. 



In those families which have incisives in the 

 lower jaw only, these exhibit simple trenchant 

 crowns, which slant horizontally forward ; and 

 being opposed only by the hardened gum of 

 the upper jaw, the function they perform 

 during the act of feeding is rather that of 

 breaking or tearing, than cutting. The action 

 is accompanied by a swinging movement of 

 the head forward, the powerful muscles in- 

 serted into the occiput along with the elastic 

 ligamentum nuchae, rendering such a motion 

 almost effortless. In (Egosceridae, Bovidae, and 

 Cervidse generally, where the incisors form a 

 broad line at the expanded tip of the lower 

 jaw, the extent of their grasp is considerably 

 increased by the prominent position of the 

 canines on either side. These latter partake 

 of the function ascribed to the former, and 

 their aspect is so similar that many ana- 

 tomists have been led into error respecting 

 their true nature. In the Giraffe the canines 

 present divided crowns, and are not placed 

 so far in front ; nevertheless, they are closely 

 applied to the outer incisors, the whole series 

 together forming a semicircle. 



The characters of the molar teeth chiefly 

 demand consideration in this place. These, 

 though presenting every variety and modifi- 

 cation of contour in the different families, 

 manifest at the same time a certain uniformity 

 of type throughout the entire order. A sin- 



