108 BRITISH LIZARDS 



distal end exhibited a plain, smooth surface, no muscles 

 being visible. Closer inspection at once revealed the 

 spaces into which these eight muscles fitted, seen as 

 holes dipping into the distal portion of the tail. The 

 appearance of the two ends is seen in the accompany- 

 ing illustration. 



Taking next the portion of the tail which had come 

 away from the body, I refractured this in several 

 places, with precisely the same results. In each 

 fracture the proximal portion retained the eight 

 muscles, while in each distal portion the positions 

 into which these muscles fitted were seen as holes. 

 The shape of each of these muscles was roughly tri- 

 angular, thick at the proximal attached end, tapering 

 to a point at the distal separable end. In doing this, 

 I found that the fracture always took place at the 

 same point as regards the muscles, nowhere else. I 

 next dissected one of the fractured pieces of the tail. 

 The integument is extremely tough, and difficult to cut 

 in the slow-worm. To the naked eye, as one dissects 

 it, this skin appears to be disposed in two layers, — an 

 external thick layer covered by scales, and an internal 

 thin layer. The external thick layer strips off all 

 round the tail, leaving the thin internal layer, which is 

 an investing membrane for the tail. It is whitish in 

 colour, and tough to dissect. An incision was made 

 along the whole length of this internal layer of tissue, 

 in the median dorsal line. This was carefully reflected 

 laterally, with the result that the eight muscles came 



