20 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.73 



strictly on vegetable matter, and the stomachs of the specimens collected con- 

 tained the leaves of one of the common trees. On breaking off a hollow limb of a 

 tree, at San Pedro, a specimen was found so tightly wedged within that it could 

 be secured only by cutting it out with a small hand ax. They have the same habit 

 as our chuckwalla (Sauromalus 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 ta 

 seize whatever comes within reach. 



In Gtenosaura hemilopJia there is great variation in the height and 

 length of the dorsal crest and the point at which the enlarged series 

 of scales stops on the back. Also there is great variability in the size of 

 the large caudal scales and of the -keeling on the scales of the limbs. 

 Perhaps the greatest variation is in the color of the individuals. The 

 black markings which serve as one of the most striking characteris- 

 tics of the species vary in number, size, and shape. The ground color 

 includes all shades between a pale yellowish gray to a dark slaty 

 brown. Indeed, the diversity is so great as to lead one to doubt the 

 distinctiveness of several species that have been described since hemi- 

 lopha was first described. Blainville,'^ prior to the establishment of 

 this species, described and figured it, calling it Iguana acanthura,. 

 thinking it to be Shaw's acanthura. For many years workers confused 

 this species with acanthura. Cope, in 1863,^^ was the first to recog- 

 nize the distinction and accordingly published his description, taken 

 from four cotypes, received from Cape St. Lucas, Lower California. 

 He placed it in the genus Cyclura, but later, 1866, placed it in the 

 genus Gtenosaura. 



In 1882 Bocourt ^® described Gtenosaura interrupta from specimens 

 of hemilopha collected by M. Botta in Lower California. An exam- 

 ination of the types in Paris, and one of the cotypes in the British 

 Museum, leaves no doubt as to their being true hemilopha. They 

 agree in every respect with Cope's types, in Washington. 



The species, insulana, based upon specimens from Ceralbo Island 

 and conspicuosa from San Esteban Island, were described in 1919 by 

 Dickerson.^" 



Concerning these species Van Denburgh says: 



With good series of specimens from both these islands and from San Pedro 

 Nolasco Island and the cape region of Lower California before me, I am unable 

 to detect any difference in proportions or in coloration, or in the size of the 

 spines of the caudal whorls, or the height or length of the dorsal crest, which 

 are not fully covered by individual variation in each locality. As regards the 

 keeling and mucronation of the scales of the legs and foot, the same is true, 

 great individual variation in the strength of the keeling and mucronation being 



"Blainville, de, Nouv. Ann. Mus., vol. 4, p. 288, pi. 24, flg. 1, 1835. 

 "Cope, Proc. Acad. Nat. Sci. Philadelphia, pp. 105-106, 18r)3. 

 "Bocourt, Le Naturaliste, vol. 2, No. 6, p. 47, 1882. 

 so Dickerson, Bull. Amer. Mus. Nat. Hist., vol. 41, pp. 461-462, 1919. 



