The Swifts 



of running on the hind limbs, as do some of the lizards already 

 described Crotaphytus, Callisaurus and Holbrookia. Although 

 the feet are not provided with adhesive disks or pads, these 

 creatures find a footing upon almost perpendicular cliffs, over 

 which they may be commonly seen darting about, in search of 

 insect food or scurrying away from the human intruder. Cap- 

 tive specimens are hardy if kept perfectly dry and very warm. 

 Their cages should be so situated as to have sunlight for the 

 greater part of the day. If deprived of the sun they seldom 

 show a desire to feed. Mealworms and grasshoppers form a 

 good diet. To provide the specimens with water, it is best to 

 take a small branch, dip this in a pail and place it in the cage. 

 They will be attracted to and drink the hanging drops, while 

 a small pan of water in the cage might pass unnoticed for 

 days. 



The Genus Lysoptychus : Following the Small - scaled 

 Swifts comes a genus containing a single species, which, in general 

 characters of scalation, stands midway between Via and Scelo- 

 porus. The scalation of the head and body appeals more strongly 

 to the latter genus, but there is a fold of skin under the throat. 

 The species is brown above, with faint darker markings in the 

 form of transverse blotches. There is a blue patch on each 

 side of the abdomen. It measures seven inches in length and 

 is technically known as Lysoptychns lateralis, Cope. But one 

 specimen is known. It was taken near San Diego, Texas. 



The Spiny Swifts, Sceloporus. The species of this genus 

 are considerably more difficult to identify than the lizards of 

 the genus Uta. The arrangement of the latter in the form of 

 a descriptive key is greatly facilitated by the strong characters 

 displayed in the scalation of the back. Among the species of 

 Sceloporus, there are no such sharply defined characters and in 

 order to correctly identify the confusing array of North American 

 species the student must note the different phases of scalation 

 of the head. With this knowledge at hand it will be found that 

 the different species fall into several groups, and identification 

 is greatly simplified. There is, however, a considerable amount 

 of variation to be seen among these lizards and the observer 

 may be confronted with frequent specimens that defy adaptation 

 to the groups in which they really belong. It might be said 

 that this genus and Cnemidophorus , are by far the most puzzling, 



126 



