GENERAL CHARACTERISTICS. 



159 



broad, and with five toes in front, four 

 behind. The first digit of the fore-foot is 

 shortened, and does not touch the earth. 

 The claws of the Felida are perhaps more 

 dangerous weapons than their teeth. Usually 

 the members of this group slink quietly about 

 on velvety feet, the sickle-shaped claws, sharp 

 as razors, withdrawn in the sheaths formed 

 by folds of the skin on the back of the paws, 

 being held back in that position by strong 

 elastic ligaments. In walking and in playing 

 the claws are not protruded, and thus escape 

 being worn away, and remain always sharply 

 cutting. But when in action the claws are 

 exserted by the powerful contraction of the 

 flexor muscles of the toes effecting a rotatory 

 movement of the last joint, to which the claws 

 are attached. As soon as the contraction of 

 the muscles ceases the elastic ligaments bring 

 them back to their normal position. The 

 cat can thus stretch out its claws at will; as 

 soon as this exertion of the will comes to an 

 end they dart back into their sheaths as if 

 by the action of a spring. The cheetahs or 

 hunting-leopards, which have long legs like 

 the Canida, do not possess this structure of 

 the toes. 



The strong and formidable dentition varies 

 within only very narrow limits. The incisors 

 are small, close-set, sharp, and adapted for 

 gnawing bones. The frequently enormous 

 canines are curved, pointed, sharp on the 

 hinder edge, and grooved on the outer side 

 with longitudinal furrows. In the upper jaw 

 there are three premolars, the first of which, 

 small and conical, disappears altogether in 

 the lynxes; the second, sharp and laterally 

 compressed, has a sharp median blade-like 

 cusp; and the third, the carnassial, with two 

 broad sharp cutting lobes, has a small internal 

 rounded heel. Immediately behind this car- 

 nassial there is a very small tubercled tooth, 

 the only true molar in the upper jaw. In 

 the lower jaw are two premolars with sharp 

 median cusps, and a carnassial with two 

 sharp lobes but without a heel, this carnassial 



being a true permanent molar. The upper 

 tubercled tooth and the lower carnassial are 

 absent in the milk dentition, in which we find 

 the same arrangement as in that of the 

 hyaenas, namely, that the last premolar both 

 in the upper and the lower jaw plays the part 

 of a carnassial. This form of tooth thus 

 becomes in the present as in the previous 

 families shifted in position in the permanent 

 dentition, in which it occupies the next place 

 behind. 



The dental formula is thus as follows: 



Milk dentition: 



3 ' i ' 3 ' 



= 26. 



Permanent dentition: 



3 i 2 o 



3 ' i '3 ' 



= 30- 



3 i 2 i 



The longitudinal or sagittal crest of the 

 skull is not so prominent as in the hyaenas 

 and the Canida, but the ridges at the back of 

 the skull are very highly developed ; the very 

 short-levered jaws, accordingly, possess, with 

 an equal bulk of masticatory muscles, much 

 greater strength than longer jaws, such, for 

 example, as those possessed by the Canida. 

 The muscles of mastication are indeed re- 

 markably powerful, a fact to which the wide 

 sweep of the zygomatic arches in this case also 

 bears testimony. 



Among the anatomical features we mention 

 only the tongue, which is covered with horny 

 warts with points directed backwards, and 

 acts like a rasp. The Felida can draw blood 

 by licking. The females have eight teats, 

 which lie in pairs both on the breast and the 

 abdomen. 



Distributed over the whole earth except 

 Australia, Madagascar, and the Antilles, the 

 Felida lead almost everywhere the same 

 nocturnal life. They hunt especially after 

 living prey. They are greatly assisted in the 

 chase by the acuteness of their hearing and 

 their sight, and their extraordinarily change- 

 able pupils adapt themselves in the most 

 striking manner to the quantity of light that 

 reaches them. The sense of touch is very 

 highly developed in the hairs of the whiskers ; 



