502 



THE NATURE BOOK 



A Slow Worm's under ja\\"s are firmly 

 united in front. A snake's under jaws 

 are loosely united, and \\'idely distensible. 

 A Slow Worm's tongue, \\hich is usuall\' 

 black, though I ha^'e known purple, and 

 even pink, variations, is notched at the 

 tip. and flickers momentarily ; a snake's 

 tongue, which I ha\'e alwa3's found black, 

 is deeph- forked, and quivers for a per- 

 ceptible time. 



A further well-marked distinction is to 



A COMPLICATED SLOW WORM. 



be found in the under surfaces of the two 

 reptiles' bodies. Forward of the tail, 

 which commencement is marked in both 

 by an aperture, the Slow \\'orm presents 

 four or five parallel rows of scales, while 

 the snake shows a single row of plates. 



The main cause of confusion between 

 Slow Worm and snake lies no doubt in 

 the fact that the former possesses no 

 external limbs. It is probable that a 

 limbless lizard is a degenerate form. 

 However this may be, the Slow Worm 

 has reduced limbless progression to a fine 

 art, for it must be remembered that in 

 comparison with a snake he is, in a sense, 

 handicapped by his own smoothness. 



A Slow Worm is highly polished all 

 over. One might almost suppose that he 

 had received a thick coat of varnish to 

 smooth down the slight asperities of his 

 scahng. If a fingernail be passed along 

 his under surface from tail to head, it 

 uiU be found to catch at intervals in the 

 hard muscular tail, but to slide smoothly 

 over the soft, yielding body. One may 

 assume from this that in the tail portion the 

 hind ends of the scales form slight trans- 



\-erse ridges. Such ridges would, of course, 

 assist the Slow Worm in movement, and 

 their absence from the body portion is 

 probably balanced by the fact that the 

 latter admits of easy indentation, and so 

 adapts itself naturally to ridges and 

 depressions in the ground. 



It is instructive to place several Slow 

 Worms on a large pane of glass, and to 

 obser\'e how every trifling inequalitv of 

 surface is taken advantage of, so that, 

 eventuall}', all reach the edge. 

 Two of them meeting will push 

 off against each other, and in this 

 case victory, so far as progress is 

 concerned, goes to the lightest. 

 The object of each Slow ^^'orm 

 is e\ddently to discover some 

 minute projection or depression 

 against which he may thrust 

 either his head or some portion of 

 his tail. With such a point 

 d'appui (it need only be a slight 

 one) he can, by muscular eft'ort, 

 swing from side to side until he 

 finds a second point which pre- 

 sents some mechanical advantage, 

 or a combination of points, which 

 enables him to move in the direc- 

 tion on which he has set his slow-mo\-ing 

 but tenacious reptile mind. Given this 

 power on glass, the smooth, delicate and 

 exquisitely balanced motion of the Slow 

 ^^'orm in his natural surroundings need 

 hardty excite surprise. He flows as a 

 peaceful winding stream. 



Moreover, he can climb. If a Slow 

 ^^'orm be confined in a rectangular cage 

 he will often be found standing almost 

 straight on end at one of the junctions of 

 the sides. Sometimes he will dispense 

 with the assistance of a corner, and rear 

 a considerable portion of liimself against 

 the flat. In both cases the weight of the 

 extension eventually proves too great 

 for the support, and he topples back- 

 wards. 



I am inclined to think that the main 

 locomotive power of a Slow Worm centres 

 n^imd his tail vertebrse, and that he can 

 onh' be fairl\' described as " slow " when, 

 as is very frequently the case, he has 

 lost a large proportion of these useful 

 adjuncts. The perfect tail in the adidt 

 is more than half the total length. 

 " Blind " Worm is, of course, a mis- 



