348 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXIII. 



neck so as to compel the former to lie permanently over the back and the 

 squirrel be placed on a thin branch, it will be seen to make vain attempts 

 to retain its balance, the tail will struggle with its bonds in the endeavour 

 to become free and, if the surface be smooth, the animal, though violently- 

 clutching at its foothold, may tumble completely over and cling with its 

 flexed claws to the undersurface of the branch. As the performer upon 

 the tight-rope keeps his balance by raising or lowering a long wand which 

 he holds within his hands so has Nature for the same purpose supplied this 

 creature with a living and pliant wand and the longer it may be, the more 

 powerful, accurate and sensitive will be the function it performs until, as 

 in this species, it becomes longer than the body which it balances and 

 requires to be coiled away for protection over the back. On occasions the 

 Flying Squirrel completely inverts the normal position of the body and 

 hangs hack downwards on to the undersurface of the branch. The tail, 

 under such conditions, becomes curled round the branch from which the 

 animal is suspended, and its position cannot but suggest to the mind that 

 it actually is in use as an organ of support, and indeed it would only 

 require a slight increase in the muscular tension in order to become so. 

 Now in this striking attitude we may possibly detect one of the evolutionary 

 gradations in the development of tbe prehensile tail, a trace of a gradual 

 passage from an organ of equilibration to an organ of prehension, from an 

 organ which in the Flying Squirrel maintains a wonderful balance upon the 

 tree-top to an organ which grasps the branches and sustains the body even 

 in so marvellous a degree as is seen in the Cebidse of the New World. 



Though descent from a higher to a lower level is peculiarly an aerial 

 motion yet the animal can well climb face downwards along the trunk of 

 a tree or, by lowering the fore limbs while still retaining the grasp with 

 the hind limbs, may allow itself to sink gently from a higher to a less 

 elevated branch. The descent of the tree-trunk is head foremost ; the 

 body is closely applied to the tree and the mode of progression resembles 

 a succession of scrambling leaps. The fore feet are somewhat separated 

 aijd the claws check the downward motion ; the hind limbs are prolonged 

 backwards and the outer two or three claws cling into the irregularities of 

 the surface and sustain the body. The hind feet appear to have under- 

 gone a partial rotation from their normal anatomical position, for the toes, 

 which are outermost when seated on the ground, have become innermost 

 when the limb is backwardly extended during the descent of a tree, but 

 the movement does not seem to attain its object in complete perfection for 

 it is usually but the inner two or three claws which meet the surface and 

 only in very favourable conditions can all five be called into action. The 

 tail, which if unrestrained by any muscular effort must hang downward 

 over the animal's back, is rigidly maintained in an upward perpendicular 

 position ; the parachute is almost entirely hidden and it is only when the 

 limbs become widely outstretched that any considerable extent of its 

 surface appears in view which at times may give the animal a most fan- 

 tastic shape. 



The day is passed in a state of sleep during which the squirrel lies 

 curled away in a sheltered hole or quiet corner of the tree. The body is 

 coiled and rests either on its side or belly : the head is turned down 

 towards the tail and tucked in between the hind limbs which are carried 

 forwards to protect it on each side and the fore limbs are flexed beneath 

 the chest. A closely allied species, Fetcturista 2Mllipensis, has been de- 

 scribed as "lying on its back with the legs and parachute extended, a 

 position it is fond of in sultry weather." I have never seen a similar 

 attitude in this species and it is possible that a posture adopted for the 

 purpose of cooling the body by a species which inhabits the tropical forests 



