330 DR. H GtADOW ON EVOLUTION [Mar, 20, 



counting these also the total sum would be 8 to 10 as stated by 

 Boulenger, scarcely 10-12 as described by Giinther. 



Tibia with only 2| rows of scutes. 



Femoral j^ores from 19-22. 



Coloration. — Throat whitish yellow, with a faint blue tinge 

 across the middle. Collar black in the adult ! Chest and belly 

 black with many white specks on the sides of the body. The 

 thighs, legs, and the whole tail are uniformly reddish yellow in 

 the youngest foi'ms and in the immature ; in the adult the thighs 

 are blue-black and chequei-ed with white. The preanal region is 

 blue ; the tail l^eneath is speckled dusky. 



Upper parts (youngest forms) : 3 pairs of thin stripes ; mid-field 

 broad and buff. 



Immature : the 3rd pair of stripes is partly vanishing on the 

 rump, so that field II. is merging into the buff of the mid-field. 



Adult : the first pair of stripes begins to be cut up by the 

 encroaching black of field I. and by the black of the lateral field. 

 The result is a light brown or buff ground-colour, with only one 

 pair of pale stripes, and mottled with black on the sides of the 

 body. 



The absence of light spots in the fields and in the vanishing 

 stripes constitute a remarkable pattern in this large and com- 

 pletely isolated kind of lizard, 



Cnemidophorus gularis Baird, 



The collar is composed of several rows of large scales, and the 

 posterior margin of the collar is formed entirely of large scales, 

 without granules. The posterior side of the forearm is covered 

 with one or more rows of large polygones or scutes, instead of 

 granules ; 6 pale stripes persist as unbroken lines. The dark 

 fields are at first spotless, but soon a row of pale, mostly whitish 

 spots appears in the first and second fields, without breaking up 

 these fields (text-figs. 69 & 70). 



It is not easy to abstract a satisfactory, furthei' definition from 

 Cope's writings of what he understood by his C. gularis gularis. 

 The femoral scales are said to be in 6-8 rows. The femoral pores 

 are stated, in the key, to vary from 18-23, but in the text 

 specimens with less than 16 are mentioned. The frenocular 

 " occurs occasionally." The chest of the males is black, while the 

 scales of the belly are margined with black ; there are light spots 

 on the flanks below the first stripe. 



Amongst an apparently large number of specimens from 

 Chihuahua Cope mentions some, distinguished by him as G. g. 

 gularis ohsoletus, with wider and very obscure stripes, and with 

 small obscure spots in the fields. Some of these specimens were 

 the largest of the collection. In others, including " a good many 

 small specimens," the stripes were wider, and the field -spots 

 enlarged so as to be confluent occasionally with the light stripes. 



