318 DR. H. GADOW OX EVOLUTIOX [Mar. 20, 



collected a sufficient number of specimens, has its characteristic 

 type : local clans of this small lizard : — 



I. The Basin of the Rio Balsas. — There are no C. deppei to the 

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

 the south they are separated from their kindred by the densely 

 wooded and elevated intricate mountains of the Sierra Madre del 

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



The Balsas clan of 0. deppei is noteworthy for the greater 

 number of femoral scales, the average number of femoral pores, 

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

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

 developed stripes on the mid-back. 



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

 Sierra Madre, in Guerrero. — Average number of femoral scales, 

 combined with the greatest number of pores ; conspicuously 

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

 not black ; collar, chest, and belly black. 



III. The Lowlands of Southern Guerrero. — Smallest number 

 of femoral scales and pores ; 7-10 sharp stripes, while reddish 

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

 and the first stripe tends to break up into beads. Otherwise like 

 Clan II., with which these southern specimens are geographically 

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

 mens from near Miahuichan, which lies on the southern outlying 

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

 in this respect with Rincon at the foot of Los Cajones. The 

 single Cajones sj)ecimen is the most blue-throated of the whole 

 Tierra Colorada clan, and the Miahuichan specimens are lemark- 

 able chiefly for the partial extent of blue and l)lack upon the 

 throat. 



IV. States of Oaxaca and Vera Cruz. — Average, or great, 

 number of femoral 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 stripe 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 different districts, and therefore 

 aflbrd no sufficient basis. 



Now, it is quite conceivable that in two geographically separate 

 clans the following combinations might become universal. 



A. Supraoculars 3 ; f emorals 7 ; pores 1 9 ; stripes 7 ; fields red ; 



thi-oat and collar black. 



B. Supraoculars 4; f emorals 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 



