XIII PHYLUM CHORDATA 505 



nail. There is a short, soft muzzle. Either one or two remark- 

 able median horns are borne on the nasal region, not attached 

 directly to the skull : these are epidermal structures which are 

 formed of a dense aggregation of slender fibre-like elements. 

 The eyes are small, the auditory pinnae well developed. The 

 surface is devoid, or nearly devoid, of hairs, and the skin is 

 enormously thick and in some species thrown into deep folds. 

 The tail is narrow and of moderate length. 



The Hyraxes are small, somewhat Rabbit-like animals, with 

 slender limbs and vestigial tail. There are four functional digits 

 in the manus and three in the pes, all provided with short, flat 

 nails, except the innermost of the pes, which has a curved claw. 

 The body is covered with soft fur. 



The Elephants, the largest of existing terrestrial Mammals, have 

 the limbs much more typically developed than in the true Ungu- 

 lates, there being five comparatively short digits, enclosed in a 

 common integument in each foot, all of them in the fore-, and 

 three or four in the hind-foot, terminating in broad, flat nails, 

 or hoofs. The weight of the body is borne on an integumentary 

 pad forming the sole of the foot. The limbs are very stout and 

 pillar-like, and the thigh and leg when at rest are in a straight 

 line, instead of being, as in the TJngulata vera, placed nearly at 

 right angles to one another — a circumstance which gives a charac- 

 teristic appearance to the hind-quarters. The nasal region is 

 produced into a proboscis or " trunk," a mobile cylindrical ap- 

 pendage, longer than the rest of the head, at the extremity of 

 which the nostrils are situated. There is in the male a pair 

 of immense tusks — the incisors of the upper jaw. The eyes are 

 small, the pinnae of the ears enormous. The tail is small, and 

 has a tuft of hairs at its extremity. The skin is very thick, and 

 provided with only a scanty hairy covering. 



In the Carnivora vera the typical number of digits is sometimes 

 present ; or, more usually, there are five in the fore-, and four in the 

 hind-foot, or four in each. The extremities of the digits are pro- 

 vided with compressed, curved claws, which may be very long and 

 sharp, when they are capable, when not in use, of being retracted 

 into a sheath of skin situated at their bases ; or relatively short 

 and blunt, when they are incompletely, or not at all, retractile. The 

 Dogs (Ganidce) and Cats (Felidm) are digitigrade, the Bears 

 ( Ursidce) and allied groups plantigrade. The Otters (Lutra) differ 

 from the rest in having short limbs with the toes connected by 

 webs of skin. 



The Pinnipedia (Fig. 1121) have the proximal segments of the 

 limbs short, so that the arm and thigh and nearly all the fore-arm 

 and leg, are enclosed in the common integument of the trunk ; the 

 manus and pes are elongated. The Earless Seals (Fhocidce) are 

 much more completely adapted to an aquatic life than the Eared 

 VOL. II II 



