594 MAMMALS. 



carnassials, while the molars are often like those of Marsupials. The 

 brain seems to have been small. 



Examples : —Hy(Enodon, Pterodon, Proviverra, Arctocyon. 



Order 7. Insectivora. 



This order includes hedgehog, mole, shrews, and related 

 mammals. There is much diversity of type, so that a 

 statement of general characters is very difficult. 



Most Insectivores run about on the earth; the mole 

 {Talpd), and others like it, are burrowers; Potamogale, 

 Myogale, and others are aquatic; Tupaia and its relatives 

 live like squirrels among the branches; and the aberrant 

 "flying Lemur" — Galeopithecus takes swoops from tree 

 to tree. 



Most feed on insects, but Galeopithecus and some other 

 arboreal forms eat leaves as well, the moles eat worms, 

 Potamogale is said to feed on fish. 



The body is usually covered with soft fur, but the hedge- 

 hog (Erinaccus) is spiny, and so to a less extent is Centetes, 

 the ground-hog of Madagascar. The digits, usually five in 

 number, are clawed, and the animals walk in plantigrade 

 or semi-plantigrade fashion. In most, the mammae are 

 thoracic or abdominal ; in Galeopithecus, there are two pairs 

 in the axillary region. 



The cranial cavity is small ; the skull is never high ; the 

 facial region is long ; the zygomatic arch is slender or 

 absent. Except in Potamogale, there are clavicles. 



There are more than two incisors in the mandible. The 

 enamelled molars have tuberculated crowns and well-de- 

 veloped roots. In many cases it is not easy to distinguish 

 / the usual division of the teeth into incisors, canines, pre- 

 molars, and molars, but in many the dentition is typical — 



3, I. 4, 3 = 44- 



The cerebral hemispheres are smooth and leave the 

 cerebellum uncovered; the olfactory lobes are large; the 

 corpus callosum is short and thin. Thus, as regards the 

 brain, the Insectivora represent a low grade of organisation. 



Except in Galeopithecus, the stomach is a simple sac ; the 

 intestine is long and simple, but' the vegetarian forms 



