FRAGILITY OF THE TAIL IN LIZARDS 109 



off with it, leaving the caudal vertebrae lying free in 

 the dissection. The appearance of the integument 

 with the muscles attached is seen in illustration, which 

 gives a better idea of it than any description. Turn- 

 ing next to the condition of the vertebrae, it was with 

 the greatest interest that I found them to be intact. 

 The separation had taken place at the intervertebral 

 articulation at both ends of the fractured piece of tail, 

 and not in the centre of the bodies of the vertebrae as 

 supposed. I photographed this portion of the caudal 

 vertebral column, and it is here reproduced. 



So that, in this case at any rate, when the tail was 

 broken off, the fracture did not take place at the 

 cartilaginous septum, as is said always to happen. 



Looking closely at the arrangement of the muscles, 

 it was easily seen that their arrangement was curiously 

 adapted to permit of their readily separating. This 

 arrangement is best described perhaps by the term 

 " dove-tailed." They fit into each other just as the 

 handle of a cricket bat is dovetailed into the blade. 

 And, further, they separate from each other just in 

 the same way that the handle of a bat is forced 

 apart from the blade, so that when in process of 

 separation they look like the fingers of one's two 

 hands interdigitating. 



These eight muscles are not equal in size, nor are 

 they disposed at equal intervals round the vertebral 

 column. Six of them are longer than the other two, 

 the two short ones, which are the thickest, being 



