156 INSECTIVORA. 



gray beneath. As the tips of the hairs are tinged with a yellow hue, the 

 precise tint of the fur is rather indeterminate, and is changeable, accord- 

 ing to the position of the hairs which are exposed to view. 



It is presumed that the long tail of the Pentail is used for the pur- 

 pose of balancing itself in its progress among the branches of trees ; but 

 this conjecture is only problematical, as the habits of the animal are not 

 yet known. 



The Tupaiadse are an interesting fanriiy of Insectivora in a scientific 

 point of view on account of the presence ol several well marked anatomi- 

 cal peculiarities. As already stated the most important of these is the 

 osseous ring that completes the posterior part of the orbit of the eye. 

 In all other specimens of the order Insectivora a communication exists 

 between the orbits and the spaces occupied by the temporal muscles 

 which act upon the lower jaw. In this peculiar conformation of the 

 TupaiadcC, therefore, we observe an approach to the structure of the 

 insectivorous monkeys. The eyes project sufficiently to enable the ani- 

 mal to see backward almost in a straight line. The small but sharp nails 

 that arm the five toes of the plantigrade feet are sufficiently elevated 

 to be spared from friction against the ground. The name Tupaia is given 

 by the natives of Sumatra both to the members of this family and to the 

 squirrels which they so strongly resemble. The fossil remains of the 

 Omoinjs have been found in the Pliocene deposits of the United States. 



