SQUIRREL FAMILY GROOVE-TOOTHED SQUIRREL 1243 



with a white spot between the ears, and another on each side of the muzzle. On 

 the other hand, in the pygmy African flying squirrel the mboma of the natives 

 the length of the head and body is only eleven inches, and that of the tail five and 

 one-fourth inches; the color of the upper parts being dark grizzled gray, while 

 beneath it is yellowish white, with the tail uniform pale brown. 



The habits of these animals appear to be very similar to those of 

 their Asiatic allies. In climbing tree stems, preparatory to taking 

 their flying leaps, it is said that they use the scales at the root of the tail to aid in 

 obtaining a hold on the bark. 



THE SQUIRREL FAMILY 

 Family 



The Squirrel family, which includes the true flying squirrels, ordinary squirrels, 

 marmots, and susliks, is distinguished from the last by the absence of scales on the 

 tail, and the presence of distinct bony (postorbital) processes defining the hinder 

 .border of the upper half of the socket of the eye. Moreover, when a parachute- 

 like membrane is present, it is supported by a rod of cartilage arising from the wrist. 

 The palate is broad; and there are generally two pairs of premolar teeth in the 

 upper, and one in the lower jaw; but the first upper premolar is small, and may be 

 shed or wanting. The molars have roots, and in the young state at least have their 

 crowns surmounted by tubercles, but in the adult they often have deep wavy 

 enamel folds, forming transverse plates extending partially across the crown. 



Till quite recently the members of the family were divided into two groups, or 

 subfamilies, according as to whether they are arboreal or terrestrial in their habits; 

 the first group including the true squirrels and flying squirrels, and the second 

 comprising the susliks and marmots. From a careful study of their dentition, Dr. 

 Forsyth-Major has, however, come to the conclusion that this arrangement is an 

 artificial one; he accordingly classes them under three groups, of which the first 

 includes the true squirrels, susliks, and marmots, the second the flying squirrels, 

 and the third the Oriental pygmy squirrels. 



THE GROOVE-TOOTHED SQUIRREL 

 Genus Rhithrosciurus 



According to the above-mentioned scheme, the first representative of the family 

 is the Bornean groove-toothed squirrel (Rhithrosciurus macrotis}, which is the sole 

 member of a genus easily characterized by the presence of a number of vertical 

 grooves on the front of the incisor teeth. Much larger than the common squirrel, 

 this species has an enormous bushy tail, long, tufted ears, and black and white bands 

 along the flanks. The molar teeth a're of a simpler type than in any other member 

 of this family. 



