1906.] IX MEXICAX LIZARDS. 313 



note that some of these variations seem to coincide with geo^ra- 

 phical districts. 



Rio Balsas: 34 specimens (text-fig. 71 E, F). — The general im- 

 pression made by these specimens is that they are rather eflfacing 

 than inci'easing or emphasising their stripes on the mid-region of 

 the back. Only stripes 1 and 2 are always white, while the third 

 pair is often thin and dull. The chief variations occur in this 

 mid-field, Avhich is enclosed between stripes 3-3. In the 9-striped 

 specimens stripes 4-|-5-)-4 always form a dull field or complex. 



The chief variations are as follows : — 



(1) The space between stripes 3-3 is lined with a dull brown 

 band on either side, enclosing a central, rather broad and green 

 mid-stripe, which is sometimes so broad it can scarcely count as a 

 stripe, looking rather like the pale mid-field of a 6-striped lizard. 

 Such 6- or 7-striped specimens are represented by 1 very young, 

 2 adult females, 1 immature S , and 4 large adult males. 



(2) This 4th or central stx-ipe is dull or dusky, and lined on 

 either side by a thin whitish line, the beginnings, or remnants, 

 of stripes 4-4, and there is in most cases a central, very weak and 

 pale 5th streak which extends from the occiput over the neck, 

 rarely to between the shoulders. Such 8-striped specimens are 

 represented by 2 very young examples and by 1 1 adult females, 

 in only three of which the strij)es 4-4 are at all well defined. 

 In one 7-striped male, 69 mm. length, the central green stripe 

 shows a faint indication of being divided in the centre by a thin 

 dark line ; a transitional stage from the 7- to 8-strij)ed condition. 



(3) As before, but the stirpes 4-4 are better marked, and the 

 5th, impaired streak extends from the head to the middle of the 

 back, rarely to the rump. Such more or less comj)letely 9-striped 

 specimens are 6 adult females and 6 adult males. 



Field I. is always conspicuously black or black-brown in the 

 females, and the lateral band or field below it is dull and incon- 

 spicuous. 



In the males, field I, is mostly dull ashy brown, while the lateral 

 field inclines to brick-red, often with strikingly pretty efiect. 

 But there are no white spots in any of the fields nor in the lateral 

 field. 



All the under parts of the females are white, more or less 

 mother-of-pearl, with an occasional tinge of gi'een or bluish 

 towards the flanks. The under surface of the tail is white, 

 bordered with dusky or bluish colour. 



In the males the under jaw, whole throat, collar, chest, and 

 abdomen are uniform bluish black, and this extends over the 

 preanal region, and over the under surface of the fore and hind 

 limbs. The tail is white, bluish towards the sides. 



In both sexes stripe 1 extends upon the front of the thigh, 

 reappears on the whole of the posterior side as an unbroken white 

 line, and is continued along the side of the tail. 



Tierra Colorada : 21 specimens (text-fig. 72 B), 1 from South 

 slope of Los Cajones, and 1 from Ayutla. — This is an essentially 



