THE TREE-SHREWS, OR TUPAIAS 315 



and we thus gain a good idea of the way in which the bats may have probably been 

 derived from the Insectivores. It must not, however, be thereby supposed that the 

 cobego is in any sense the missing link between these orders ; its leaf -eating habits, as 

 well as the peculiar structure of its incisor teeth, being alone amply sufficient to dis- 

 prove its claim to that position ; the insect-eating bats, which appear to be the an- 

 cestral groups of the order to which they belong, having in all probability been 

 directly derived from insect-eating Insectivores. The cobego should, indeed, be re- 

 garded rather as the sole representative of a side-branch, which, while to some extent 

 simulating the bats, never gave rise to any descendants showing the special modifi- 

 cations for true flight. 



THE TREE-SHREWS, OR TUPAIAS 

 Family 



With the tree-shrews, or tupaias, we come to the first family of the true Insec- 

 tivores, or those which are incapable of flight, and have their front or incisor teeth 

 of a normal form. 



The tree-shrews, which are entirely confined to the Oriental region, take their 

 name from their strictly arboreal habits ; and are small, long-tailed animals, so 

 closely resembling the smaller squirrels in external appearance as to be frequently 

 mistaken for them. Indeed, it appears that the native term Tupai, from which 

 these animals derive their second title, is applied indifferently by the Malays both to 

 them and to squirrels ; the affix Tana serving to denote the members of the present 

 group. That they have really nothing to do with the squirrels is shown by an ex- 

 amination of their teeth, when it will be found that, instead of the single pair of 

 chisel-like incisor teeth, they have two pairs of small incisors in the upper jaw, and 

 three pairs in the lower. 



The tree-shrews belong to a group of Insectivores characterized by 

 their upper molar teeth, having broad crowns carrying a number of 

 cusps, arranged in the form of the letter W. They are peculiar in that 

 the socket of the eye, or orbit, is surrounded by a bony ring, whereas in other 

 members of the order it is open behind. They are further distinguished from the 

 other true Insectivores not only by their completely arboreal, but likewise by their 

 diurnal, habits, as they feed entirely by day. They resemble squirrels in the gen- 

 eral form of the body and limbs, and in possessing a more or less bushy tail. They 

 have 38 teeth, of which f are incisors, \ canines, and cheek-teeth, on either side of 

 each jaw. Their feet, like those of squirrels, are naked beneath, with moderately 

 curved and sharp claws. The muzzle is sharply pointed, the ears are small and 

 rounded, and the long hair of the bushy tail is confined to its upper surface and 

 sides, the under surface having much shorter hair. 



Altogether, there are about thirteen species of the genus Tupaia, 

 Distribution , .-.,.... _ . . m , 



which have a wide distribution over the Oriental region. They are 



found in India, Burma, the Malay Peninsula, the Nicobar islands, Sumatra, Java, 

 Borneo, and the Philippines. They are very much alike in general appearance, the 



