1906.] 



IN MEXICAN LIZARDS. 



281 



the fore and hind aspect of the forearm, thigh and tibia, the 

 femoral pores and the coloration, or rathei- the pattern and its 

 modes of evolution as indicated in the various kinds irom youth 

 to age. These characters are not all of eqvial importance. The 

 scaling in front of the forearm and of the tibia is subject to 

 endless individual vai-iation in detail, even in specimens from the 

 same locality, so much so that these variations cannot be well 

 described in short terms. For instance (text-fig. 61), on the front 

 of the forearm there may be 3 longitudinal rows of transverse 

 scales, or only 2| rows, i. e. two comjjlete and a shorter, smaller row 

 intei-calated from the elbow downwaixls ; or the half row may be 

 added to the side. The sole object is to protect a given surface 

 with scutes, and this is attained in various ways. If some scutes 

 happen to be larger than usual, others are correspondingly reduced; 

 and if there should not be room enough for all the preformed 

 scutes to grow, granules fill up the spaces, the total available 

 space being of course predetermined, cf. text-fig. 61. 



Text-fiff. 62. 



Lepidosis of the under surface of the left forearm. 



A=C. immutabilis, Salina Cruz No. 1. Covered entirely with small granules. 

 B=C. sexlhieatus, North Carolina. Covered with enlarged granules. 

 C=C austraUs, Laguna, Oaxaca. With slightly enlarged granules. 

 D=(7. australis, Laguna, Oaxaca. With enlarged granules. 



The rows of scales or scutes which cover the thigh (counting from 

 the pores to the highest row on the front aspect of the thigh) are 

 often difficult to count, especially when some of the i-ows are not 

 arranged in regular lines. Frequently some scutes are intercalated, 

 representing what in other specimens has been developed into an 

 entire extra row. Thei-e are many indications that the number 

 of scales, or of the rovvs, increases with the size, with the growth 

 of the lizard, and still more likely with the growth of the species. 



