OPHIDIAN A CR OB A TS. 217 



creating a vacuum like the pedal scales of house lizards.' 

 He put some active little snakes on the ground, where there 

 was no hold for the scutae, and they ' flew about in all 

 directions.' He saw that they moved on by these quick, 

 sinuous curves — 'rapid wriggles.' 



In company with my esteemed friend, Mr. Robert 

 Chambers of Edinburgh, we made similar experiments by 

 placing some of the smooth-scaled, active snakes on a 

 boarded floor. Being extremely wild, they displayed their 

 anger and skill to perfection, and literally swam along, 

 scarcely touching the floor, and so swiftly that we had 

 difficulty in pursuing and securing them again. Some very 

 young Tropidojioti vjh.Qn disturbed flew or 'swam' about their 

 cage in the same manner. We also saw pythons climb up a 

 window-frame, and a corner of the room where no visible hold 

 could be obtained ; and after the example of Sir Everard 

 Home, we allowed the reptiles to crawl over our hands, 

 when we could feel the expansion and flattening of the 

 body by the spreading of the ribs.. I incline to agree, there- 

 fore, with the writer in Nature^ that there is a sort of 

 vacuum created by the ventral scales. Dr. Stradling 

 observed that on occasions of retreat, some snakes move in 

 such rapid and ever-varying sinuations as to baffle you 

 completely when you attempt to lay hold of them ; the part 

 you thought to grasp is gone.^ Such are the movements of 

 PituopJiis and oi Echis (p. 151). 



At the risk of being tedious, a few more words must be 

 added on this subject of progression, because we so con- 



^ ' On the Movements of Snakes in Flight,' by Dr. Arthur Stradling, C.M.Z.S., 

 Nature, Feb. 18S2. 



