THE HIPPOPOTAMUS. 231 



hermetically closing the nostrils, for they are supplied mth a 

 wonderful valve arrangement that enables the animal to do this at 

 will. The mammals that are amphibious only possess this power ; 

 but, as already described, the camel and giraffe have a similar 

 construction as a protection when breathing the sand-laden air. 



The hippopotamus has a tremendous gape, for it can open the 

 jaws to a wider extent than can readily be believed without 

 occular demonstration. It has, in fact, far and away the largest 

 mouth of any known animal. In this cavernous receptacle it 

 displays six molar teeth on each side of both jaws, very strong 

 and enormous ripping canines, forming the tusks, the upper ones 

 being nearly straight, but the lower ones curved and working upon 

 each other, so as to produce a chisel-like' edge with which the 

 animal can cut grass, vegetables, and river weeds, or uproot 

 them with the ease of an agricultural implement. It has also 

 four incisors in each jaw, the upper ones bent forward, the under 

 ones long and cylindrical. The tusks, of the lower jaw especially, 

 are harder and even of more commercial value than the ivory of 

 the elephant. Tusks of the hippopotamus have been known to 

 weigh twenty-one pounds; this is of course exceptional, but 

 conveys the idea of the formidable teeth that are hidden in the 

 closed jaws of this singular-looking beast. No ivory keeps its 

 colour so well, and large quantities of these tusks are imported 

 into England, where dentists highly value them for making artificial 

 teeth, and they are used for many other purposes. The skin is 

 destitute of hair, except a few tufts on the lips, edges of the ears, 

 and on the short thick tail. The colour is a dark pinkish-brown, 

 and marked all over with dark spots, which are almost invisible, in 

 some instances, without close inspection. The skin exudes some 

 thick, oily matter from its numerous pores, which evidently acts as a 

 protector against any injurious effects that might result from long 

 immersions in the water. 



Although the hippopotamus swims and dives with an agility 

 that is astonishing considering its bulky form, it is far from an 

 active beast when on land ; for the weight the dumpy legs have to 

 support renders its gait anything but a rapid one. The consequence 

 is that when out of the water it is not by any means a dangerous 



