8 U. S. P. R. R. EXP. & SURVEYS ROUTE IW CALIFORNIA. 



from near Fort Yuma, the large one found in the desert between Kern river and the Tejon Pass, 

 (pro-nounced Tahon ;) a country without water, not sandy, but arid, bearing artemisia, &c* 

 GEN. OBS. This animal differs from Crotaphytus, (Holbrook,) in having the upper part of the 

 body covered with quadrangular scales, instead of granulations, and the larger row of carinated 

 dorsal scales giving rise to a slight crest, no trace of which exists in Crotaphytus ; and from 

 Homalo-saurus, in the form of the marginal plates of the upper jaw. Several other genera of 

 Iguanidce present a larger row of scales along the middle line of the back, viz; : Enyalius 

 Microlophus, and Brachysaurus, but these all differ greatly from Dipsosaurus ; neither Enyalius 

 nor Microlophus have femoral pores, and the scaling of the orbit in the latter is quite different, 

 presenting a longitudinal row of large transverse plates ; the scales upon the body both in 

 Enyalius and Microlophus are much smaller, and the shape of the head is not the same. 



FAMILY III. 



LACERTID/E. 



CHAR. &quot; Saurians with an elongated body, tetrapod, with four or five free toes unequal ; tail, 

 long verticillate, conical ; cranium protected by horny polygonal plates ; a distinct tympa 

 num ; large scales beneath the abdomen ; tongue free, flattened protractile, rarely sheathed 

 at the base, notched or deeply slit at the point.&quot; (Dum. et Bib., vol. V, p. 5.) 



For further details in regard to the characters of this family, see Dum. et Bib., vol. V., p. 425. 



CNEMIDOHORUS, Dum. et Bib. 



CHAR. Nostrils in the nasal plate near its posterior border ; two supero-nasals ; palate with 

 out teeth, with a shallow triangular notch posteriorly ; scales smooth. (Dum. et Bib.) 



CNEMIDOPHORUS UNDULATUS, Nob. 



SP. CHAR.- Of moderate size ; tail very long ; nostril in the naso-rostral plate near its inferior 

 and posterior margin, just above the first supra-labial ; head, brownish above ; upper part of 

 body with three or four longitudinal bands of black, with irregular margins ; interspaces, 

 yellowish, with a tinge of red in some specimens ; sides margined with black and white or 

 light-yellow ; tail, black and light-yellow, presenting numerous transverse rows of rhomboidal 

 carinated scales ; upper part of extremities same color as sides of body ; under surface, silvery 

 gray, with a number of minute black spots upon the abdomen, throat and chin ; tail round, 

 moderately thick at base, tapering to a point ; twenty pores very distinct ; eight rows of scales 

 upon the abdomen. 



DIMENSIONS. Length of head, one inch ; greatest breadth posteriorly, half an inch ; of head, 

 neck, and body, 3^ inches ; of anterior extremities, f inch ; of foot to extremity of longest toe, 

 half an inch ; of posterior extremities, 1^ inch ; of foot to extremity of longest toe, 1 inch ; of 

 tail, 7^ inches ; total length 11^ inches. 



HABITAT. Near Fort Yuma, in San Joachim Valley. 



GENERAL OBSERVATIONS. Cnemidophorus perplexus, according to Professors Baird and G-irard, 

 has seven longitudinal yellowish lines along the back ; in all the specimens submitted to our 



