318 DR. H, CxADOW OX EVOLUTION [Mar. 20, 



collectefl a sufficient nnniber of specimens, has its characteiistic 

 type : local clans of this small lizard : — 



I. The Basin of the Rio Balsas.-^ There are no C. deppel to the 

 north of it, even a few miles away from the rivei-, and towards 

 the south they are separated from theii' kindred liy tlie densely 

 wooded and elevated intricate mountains of the Siei-ra Madre del 

 Sur, which is inhabited only by C. mexicanus var. balsas. 



The Balsas clan of C. deppei is noteworthy foi' the greater 

 number of femoral scales, the average numbei' of femoral poi-es, 

 the black-blue colour of the whole under surface of the males, 

 and the frequency of brick-ied lateral fields ; lastly, the poorly 

 developed stripes on the mid-back. 



II. Tierra Colorada, to the south of the main ridge of the 

 Sieri'a Madre, in Guerrero. — Average number of femoral scales, 

 combined with the greatest number of pores ; conspicuously 

 9-strij3ed ; adult males with two red bands on each side ; throat 

 not black ; collar, chest, and belly black. 



III. The Lowlands of Southern Guerrero. — Smallest nmnber 

 of femoral scales and pores ; 7-10 shai-p stripes, while i-eddish 

 bands are rare ; faint light spots in the first field are frequent 

 and the first stripe tends to l)reak up into bea-ds. Otherwise like 

 Clan II., with wliich these southern sj^ecimens are geographically 

 continuous. Note the difference in coloration of the three speci- 

 mens from near Mialiuichan, which lies on the southern outlying 

 slopes of the Sierra, at an elevation of 1500-1600 feet, agreeing 

 in this i-espect with Rincon at the foot of Los Cajones. The 

 single Cajones specimen is the most blue-throated of the v.'hole 

 Tierra Colorada clan, and the Mialiuichan specimens are jemark- 

 able chiefly for the pai-tial extent of blue and black upon the 

 throat. 



IV. States of Oaxaca and Vera Ci'uz. — Avei'age, or gi'eat, 

 number of femoi-al scales, with greatest number of pores. 

 Preponderance of 10-11 stripes, with development of conspicuous 

 white spots on the flanks and breaking up of the first sti'ipe into 

 beads. Absence of red bands ; black on the throat is very 

 exceptional, rare even on the collar. 



The structural characters vary too much for generalisation, 

 as shown by 26 specimens, all from Tequesixtlan. The remaining 

 34 specimens came from eight diftei-ent districts, and therefore 

 afl'ord no sufficient basis. 



Now, it is quite conceivable that in two geogi-aphically separate 

 clans the following combinations might become univei'sal. 



A. Supraoculars 3 ; femorals 7 ; pores 19; stripes 7 ; fields red ; 



thi-oat and collar black. 



B. Supraoculars 4 ; femorals 5 ; pores 16; stripes 9-10; fields 



not red ; throat and collar white. 



Either of such groups would be entitled to at least subspecific 

 rank. But there is not yet any clan known with such a com- 

 bination. As they stand, they must therefore be satisfied with 



