114 Dr. H. Gadow. Evolution of the Colour-pattern [May *2'2. 



sometimes lightened up, inditing transition to Stage B ; or blackish 

 pigment is collected in the centre and also on the inner borders of 



lines 4 4, S o that Stage C seems to be foreshadowed. On the other 



hand, there are a few aged specimens which suggest, by the mottled 

 and irregular distribution of the pigment within the broad centre 

 field 4 4 ; that they have relapsed from an 11-striped to the 8-striped 

 condition. 



Another Field of Variation in pattern and colour are the sides of the 

 body, from the ear-stripe, No. 1, down to the ventral scales. This 

 lateral region is very liable to become " ornamented " with white 

 roundish spots or patches, arranged in one or two, rarely in three 

 longitudinal rows, which begin at the thighs and decrease in distinct- 

 ness towards the arms. There are several degrees : 



1. The stripe No. 1 is complete and there is no lateral row. 

 Observed in females only. 



2. The stripe 1 is complete and below it is a short, or faint, line, 

 continuous or as interrupted spots ; rather frequent in female or very 

 young 9-striped specimens. 



3. Stripe 1 is more or less broken up into a string of white beads ; 

 below it follows a row of large, roundish white spots : one 8 T and one 

 9-striped female, and one 10-striped male; or there are two very con- 

 spicuous rows of spots : the majority of males, nearly all with 10 or 1 1 

 stripes. 



4. Same as 3, but not only line 1, but also line 2 is broken up into 

 white beads, and the two lateral rows are very conspicuous. Observed 

 in large and small males. 



The development of lateral spots is, with individual exceptions, 

 pre-eminently a feature of vigorous males. The same applies with 

 still greater force to the colour of the under parts. They are yellowish- 

 white, or with a faint bluish tinge, in the young and in the females, 

 but blue or almost black in males from the breeding season towards the 

 "winter." The dark blue is most intense on the abdomen, on the 

 chest, and on the narrow collar, extending over the under surface of 

 the thighs and arms and suffusing the throat. 



Cnemidophorus guttatus, Wiegm. 



This species is restricted to the hot parts of tropical Mexico, and 

 appears as two races, which structurally not distinguishable, are very 

 different in their colour pattern. The striped race has hitherto been 

 found only on and near the Isthmus of Tehuantepec, where it inhabits 

 the same kind of terrain as the small C. deppei but with less scanty vege- 

 tation. The spotted race is restricted to the open forests with dense 

 undergrowth, ranging from near Vera Cruz to the eastern slope of the 

 Isthmus. 



