FRAGILITY OF THE TAIL IN LIZARDS 111 



taper to the free point in the spaces made by the 

 fibrous septa in which they lie. 



2. Lacerta viridis, the Green Lizard. 

 These anatomical arrangements on which this 

 phenomenon depends are even better seen in the 

 green lizard, where the scaling of the tail adds another 

 factor not so easily made out in the slow-worm. The 

 scales in the latter are extremely small, in the green 



nm 



AjA-A. Fracture. 



AAA No fracture. 



AAA Fracture. 



A A A No fracture. 



AAA Fracture. 



A A A No fracture. 



A AjA Fracture, and so on. 



Fig. 2. 



lizard they are large and elongated. When I pro- 

 ceeded to confirm the results above described, by 

 fracturing the tail in green lizards, it was found that 

 these caudal scales have a definite position with regard 

 to the muscles. One naturally expected that the 

 fracture took place between two rows of scales, not 

 across a row, but I was not prepared to find that it 

 occurred at definite intervals of scales, and only at 

 those intervals. But, of course, it simply is that a 



