228 MR. R. SHELFORD ON '' FLYING " SNAKES. [Mar. 6, 



since in tropical jungles tree-trunks are more or less swathed in 

 lianes and parasitic creepers, the climbing of them presents no 

 special difficulty even to a limbless animal. Descent from a tree 

 by way of its creeper shrouds, we may suppose, is even more easy, 

 and is doubtless often resorted to. Some snakes, however, have 

 been seen to hurl themselves from the top of a tree and to fall in 

 writhing coils into water or bushes beneath ; in the Sadong River, 

 Sarawak, I captiired a specimen of Tropidoiiotus maculatus Edel. 

 that was swimming to shore after such a fall from a tree into 

 the river. Individuals of three species have been observed to 

 " fly" out of trees : namely, Dendrophis pictus Gmel., Chrysopelea 

 ornata Shaw, and C. cJirysochlora Reinw. My attention was first 

 called to this habit by a Dyak collector attached to the Sarawak 

 Museum, who brought in one day in 1898 a dead example of 

 Chrysopelea ornata^ and averred that he had witnessed this snake 

 shoot out of a tree and descend to the ground at an oblique 

 angle to the tree, its body being kept rigid the whole time of the 

 " flight." Not unnaturally I gave but little credence to this state- 

 ment, but my curiosity Avas stimulated when, some weeks later, a 



Text-fis'. 56. 



iCU-^ 



A ventral scale of Cliri/sopelea ornata Shaw, a, a, liiuge-lines. 



specimen of C. cJirysochlora was brought in with the same story. 

 Instructions to bring in these snakes alive were issued, with the 

 result that before very long I was able to test on the living- 

 subject the truth of the Dyak's assertions. It must be noted here, 

 that in these two snakes the ventral scales are provided Avith 

 lateral sutures, or, as I prefer to call them, hinge-lines (text- 

 fig. 56). If a living Chrysopelea be handled, it may be observed 

 that, by a forcible muscular contraction, the venti-al scales can be 

 drawn inwards, so that the snake becomes deeply concave along 

 the ventral surface (text-fig. 57, B) ; at the same time there is a 

 slight dorso-ventral flattening of the body : each scale moves on its 

 lateral hinge-lines ; Avhen the muscles working these scales relax, 

 the snake re-assumes its ordinary cylindrical shape (text-fig. 57, A). 

 In other words, during the muscular contraction the snake is like 

 a piece of bamboo bisected longitvidinaJly. As anyone can test 

 for himself by experiment, a rod of bamboo will fall to the gi'ound 

 more quickly than a longitudinally bisected rod of equal weight ; 



