94 CALIFORNIA ACADEMY OF SCIENCES. 



niiig in the general direction of temporal spines. Other 

 upper head-scales flat, each with numerous ridges and 

 granulations usually darker than ground color of head. 

 Several longitudinal series of gular scales enlarged and 

 spinose, but becoming smaller toward median line, and 

 continued back onto gular fold or folds. A series of five 

 or six large spinose sublabials, often continued posteri- 

 orly by smaller plates. Below corner of mouth, a very 

 broad spine followed by a long slender one. Two groups 

 of spines on each side of neck, lower usually larger. 

 Back and tail bearing large, scattered, elevated, keeled, 

 tubercular scales, between which smaller scales and 

 granules. Two rows of peripheral spines; lower series 

 shorter than upper and composed of much smaller 

 spines. Tail bordered with a single row of lateral spines 

 and having a small group of slender ones just behind 

 thigh. Scales on anterior surfaces of limbs large, 

 pointed, and strongly keeled. Those on chest, belly, 

 and proximal part of the tail smooth, but those on ter- 

 minal part of tail keeled. Tympanum not covered 

 with scales. Long series of femoral pores present. 

 Males usually with enlarged postanal plates. 



The upper surfaces are variously tinted with yellow, 

 brown, red, gray, or slate. A large brown patch occu- 

 pies each side of the neck. On the back are undulate 

 cross-bands or large blotches of dark brown, usually 

 edged posteriorly with white or yellow. Similar mark- 

 ings may be seen on the tail. The keels of many of the 

 large dorsal tubercles are dark brown. The head is 

 yellowish, usually dotted with brown. Its larger spines 

 are sometimes reddish. The lower surfaces are yellow 

 or yellowish white, uniform or mottled with slate or gray. 

 All markings are usually more distinct in young than 

 in old specimens, but are very variable in both, the 



