112 BRITISH LIZARDS 



certain number of scales correspond to each muscle- 

 length, and that number, as a matter of fact, is two. 

 The length of two scales is the length of one muscle, 

 so that the fracture is found to occur at intervals 

 of two scales. One cannot make the tail fracture at 

 the end of the scale next to that which covered the 

 termination of a previous fracture. The diagram on 

 p. Ill may explain this more clearly. 



Fig. 3. — Section of Tail, Lacerta viridis (diagrammatic). 



SC is spinal cord. C is centrum of vertebra, 

 D 1, D 2, are positions of the two dorsal muscles. 

 VI, V 2, „ „ „ ventral muscles. 



L 1,2,3, It, „ „ four lateral muscles. 



Note.— There are three partitions on each side, the ventral one on each side 

 holds two muscles, a ventral and a lateral muscle. 



There is thus a very well-marked metameric seg- 

 mentation in the tail of these lizards, each segment 

 being marked externally by the interval between every 

 second scale, though no differentiation is apparent. 

 Just as in the case of the slow-worm, so in the 

 green lizard, if the skin be dissected off a part that is 

 fractured, the muscles come off with it, and present 

 the same arrangement seen before. The caudal ver- 



