3. CTENOSAURA—4: DIPSOSAURUS 7_[ 



our Chuckwalla {Saiiromalus ater) of getting into crevices 

 and holding tight by puffing up the body. Large specimens 

 are very rare, as the natives kill them for food whenever 

 they find one of desirable size. They are somewhat vicious 

 when captured, and when held by the tail will always keep 

 the mouth open ready to seize whatever comes within reach." 

 Mocquard quotes M. Diguet, as follows: "On les trouve 

 en grand nombre en certains endroits de I'lle de Ceralbo, 

 principalement au bord de la mer, pendant la saison oii la 

 vegetation est suspendue; a ce moment, en effet, ce Saurien 

 se nourrit de Crabes, qu'il poursuit j usque dans la mer." 



Genus 4. Dipsosaurus 



Di-pso-saurtis Hallowell, Proc. Acad. Nat. Sci. Phila., Vol. 7, 1854, 

 p. 92 (type, dorsdis). 



The scales of the median dorsal row are slightly en- 

 larged, forming a small crest. The head is covered with 

 small convex subgranular plates. The dorsal and caudal 

 scales are small. There is one strong transverse gular fold. 

 Femoral pores are numerous. Males do not have enlarged 

 postanal plates. Digits each have a series of keeled plates 

 below. 



This genus includes three species, of moderately large 

 size, which resemble in many ways the much larger iguanas 

 of more southern regions. One species, however, may be 

 divided into two subspecies by a character which is not con- 

 stant in all specimens but is found in so large a majority 

 of them that it seems best to recognize the fact in nomen- 

 clature. Specimens of this lizard from the "Cape Region" 

 of Lower California usually, have but one row of scales 

 separating the rostral and nasal plates, while those from 

 northern Lower California, California and Arizona more 



