1903.] and Orthogenetic Variation in Lizards, etc. 113 



III. Evolution and Variation of the Colour-Pattern. 

 Cnemidoplioi'us deppei, Wiegm. (fig. 1, PI. 3). 



The pattern of this small species is always striped, the white lines* 

 1 to 4 contrasting sharply with the alternating dark fields, but there 

 is great variation within the midregion enclosed by stripes 4 4. 



Stage A. 8 White Stripes. Specimens with only 4 pairs of white 

 stripes and with a narrow uniformly dark centre field are rare. 



Stage B. 9 White Stripes. Represented by about 24 per cent., babies 

 and adult of both sexes. The white central stripe is either still short 

 and very thin, or it reaches from the neck to the tail. Occasionally 

 it is represented only by a faint row of white dots and streaks, and 

 the two lines 4 4 combine in front and behind. 



Stage C. 10 White Stripes. Represented by about 40 per cent., com- 

 prising babies and adult. The original midfield between stripes 4 4 

 is divided by a black centre line which exhibits every stage from 

 separate specks or long dots to a complete streak which extends over 

 the greater length of the trunk, leaving, however, the new pair of 

 white lines 5 5 confluent in front and behind. The modification 

 from Stage B to C seems to be brought about by a broadening of the 

 originally impaired centre line 5, in the middle of which appear tiny 

 black specks which increase longitudinally, while the white line 

 broadens out. In Stage C these new white lines are further 

 emphasised by black pigment which is more densely deposited 

 between them and the lines 4 4. 



Stage I). 11 IVldie Stripes. Represented by about 30 per cent., all 

 adult. This condition is a further development of Stage C. The 

 original midfield between 4 4 has become still broader. The same 

 applies to the black centre line, which, beginning on the middle of the 

 trunk, is rent asunder, owing to the appearance of new white tissue. 

 This splitting of the black line is continued, until at last a new white 

 and long stripe 6 is produced, which, in old specimens, may extend 

 over nearly the whole length of the back. 



The Stages A to D are so gradually connected with each other that 

 it is impossible to refer every specimen to one or other of the four 

 categories. This applies especially to those which show only 8 white 

 stripes, but with the centre field between 4 4 broad and rather pale, 

 brown or grey, much paler than the other dark fields, although 

 distinctly darker than the lines 4 4. The centre of this midfield is 



* The white lines are counto J proceeding from the sides of the body towards 

 the middle of the back. The first line passes through the outer ear, over the root 

 of the upper arm, along the sides of the body and then on to the thigh. The 

 second line extends from the upper margin of the eye to the hip joint. The third 

 begins at the posterior occipital corner. 



