OPHIDIAN A CR OB A TS. 215 



When frequently handling the young- constrictors, one has 

 been able io feci diS well as to observe the action of the ribs. 

 As they pass through the hand, you feel them expanded, 

 so as to present a flatter under surface. In Ptyas the back 

 is remarkably keeled when crawling, a section of his body 

 presenting the form of the middle diagram given below. 



Schlegel describes the forms which the bodies of various 

 snakes assume in swimming, climbing, clinging, etc. Some- 

 times they are laterally compressed, at others flattened. 

 The three figures above are on a much reduced scale, but 

 give an idea of the sections of three different snakes, 

 though each snake is capable of several such changes of 

 form. When snakes climb against the glass of their 

 cages, you may easily discern the flattening of their 

 bodies. In this action there seems to be a compressing 

 power, any hold of the scutae against a polished plane 

 being, of course, impossible ; yet without holding they seem 

 to cling ; and the ribs advance in wave-like intervals just 

 the same, with an intermediate space at rest until in turn 

 the wave is there and passes on, while from an anterior 

 portion another wave approaches, and so on. Yet the coin- 

 pressure strikes one forcibly. There is also the evident 

 support of the tail in a large python thus crawling to the 

 very top of his cage. 



Mr. Gosse observed the dilatation and flatteninc: of the 



