SNAKES OF CEYLON 55 



interval of nearly seven months elapsing between the slough- 

 ing periods, though in the rest of the year this process was 

 observed four times. 



(g) Progression : The progress of a python may be sin 

 gular. All snakes known to me move only by a series of 

 lateral undulations, so that their bodies assume S-shaped 

 curves. The python can also progress with the body extended 

 and perfectly straight. During progress wave -like move- 

 ments of the ribs can be seen beneath the skin, following one 

 another in quick succession, and reminding one of the action 

 of the legs of a centipede. Progress of this character is very 

 slow, in fact cannot be called anything but a crawl, and the 

 body oscillates slightly from side to side. It also moves by 

 lateral undulations like other snakes but only slowly. The 

 slow and laboured locomotion I believe to be due to the 

 very narrow ventral shields. The extremities of the ribs 

 being inserted into the edges of the ventrals causes these 

 bones to be very much bowed. As a result, the middle two- 

 fourths of the body breadth supports the whole of the massive 

 body weight, leaving one -fourth overlapping each side. 



I have been assured by some observers that the python 

 can, when so inclined, move as expeditiously as other snakes. 

 Personally I have never witnessed this. 



(h) Hissing : I have heard captive specimens in the hands 

 of jugglers utter a low sibilant hiss. 



(i) Sloughing : Many observations have been made in 

 various quarters on this function, which appears to depend 

 upon the general state of health and vital activities of the 

 snake. I have already remarked upon the great reduction 

 in temperature observed by Phipson in a python in the 

 Bombay Natural History Society's rooms during the period 

 of hibernation, and, with the vitality reduced to such a low 

 ebb that the snake was incapable of digesting its food, it is 

 not surprising that there was a coincident abeyance in the 

 desquamative process during this period. Specimens in 

 Madras and Travancore desquamated during the whole year, 

 and appear not to have hibernated. In India the python 

 sloughs five or six times annually as will be seen from the 

 following table of records : — 



