392 ORDERS OF MAMMALIA, 



Section III. Digitigrada. — This section comprises the 

 Lions, Tigers, Cats, Dogs, &c., in which the heel of the foot 

 is raised entirely off the ground, and the animal walks upon 

 the tips of the toes (fig. 673, c). 



As regards their general distribution in time, if the little 

 Microlestes of the Upper Trias be Marsupial, as is almost 

 certainly the case, then the order Carnivora is comparatively 

 modern, the earliest undoubted remains having been found 

 in the Eocene Tertiary. In the Eocene period, however, the 

 families of the Canidm, Viverridce, and Felidm appear to 

 have been already differentiated. The JJrsidce, Mustclidce, 

 Hyccnidce, and Phocidcc, do not seem to have made their 

 appearance before the Miocene period. In the Pliocene and 

 Post-PHocene periods almost all the existing types of the 

 Carnivora are represented by extinct forms, whilst in the 

 latter the remains of various living species are found asso- 

 ciated with other animals which have at the present day en- 

 tirely passed away. In the following are given the charac- 

 ters and chief fossil forms of the families of the Carnivora. 



Section I. Pinnigrada. — This section of the Carnivora 

 comprises the amphibious Seals and Walruses, which differ 

 from the typical Carnivores merely in points connected with 

 their semi-aquatic mode of life. The body is elongated, 

 somewhat fish-like in shape, and terminated by a short 

 conical tail. All the four limbs are present, but they are 

 very short, and the five toes of each foot are united by the 

 integuments, so as to form powerful swimming- paddles. 

 The hind-feet are placed very far back, their axis nearly 

 coinciding with that of the body (fig. 673, b). Owing to 

 this circumstance the hinder end of the body forms an 

 admirable swimming apparatus, similar in its action to the 

 horizontal tail-fin of the Cetacea and Sirenia. The dentition 

 varies ; but teeth of three kinds are always present, in the 

 young animal at any rate. The canines are always long and 

 pointed, and the molars are generally furnished with sharp 

 cutting edges. There is always a diminution of the incisors 

 below their normal number of six in each jaw, and the 

 molars are never divided into carnassials and tubercular 

 molars. 



