132 BULLETIN 17 7, UNITED STATES NATIONAL MUSEUM 



colored blotches arranged in four or five more or less irregular vertical 

 rows on the sides of the body; limbs and feet with heavy, slate-colored 

 cross bars ; lower surface of body olive-buff, of tail drab ; throat suffused 

 with cloudings of olive-gray ; reticulations of slate color extending over 

 lateroventral region and a few spots scattered on lower parts of limbs ; 

 traces of a light temporal patch bordered above by a black streak; 

 skin and scales of gular fan pale straw yellow; a pale infraorbital stripe 

 fading out just back of the commissure of the jaws. 



Dimensions. — Head and body, 137 mm.; tail, 290 mm.; snout to 

 center of eye, 27 mm.; snout to posterior ear, 44 mm.; foreleg, 61 mm.; 

 hindleg, 106 mm. 



Variations. — In the series of specimens in the National collection 

 there is considerable uniformity in head scalation. Between the 

 supraorbital semicircles there are two, three, or four irregular series 

 of scales, sometimes large and sometimes small. The occipital is 

 always small and inconspicuous; indeed, were it not for the light pineal 

 body it would be indistinguishable as the occipital. Between tlu*ee 

 and six small sharply conical scales separate it from the supraorbital 

 semicircle. The loreal rows are four to eight in number, the topmost 

 ones being always rugose like the canthals, except in the young. 



While the males often have a high dorsal crest, it is weak in a few 

 individuals. On the other hand, the females in four cases have as 

 high a dorsal crest as the majority of males, but in four other cases 

 the crest is not developed at all in the females. Thus it is evident 

 that the degree of development of the dorsal crest is not a true sexual 

 character. 



The males always have a pair of very large postanal plates, as well 

 as the high "tail fin." In one male (U.S.N. M. No. 9804) there were 

 four postanal plates, each of the original pair having apparently di- 

 vided longitudiually. The females have neither the postanal plates 

 nor the tail fin. 



The variation in pattern is considerable. While some of the speci- 

 mens show no pronounced pattern, others have a definite black mark- 

 ing, very irregular in outline, which extends across the nape, branches 

 forward to cover the temporal and most of the supraocular regions 

 and extends with more or less interruption on the shoulders and 

 anterior lateral region as a series of very uneven large and small 

 patches. One of the hzards from San Juan River (U.S.N.M. No. 74941) 

 is azure blue and mauve above, and pale blue below including the 

 scales of the gular fan, the skin of which, in this individual, is slate 

 color anteriorly, fading out to a fine powdering of very minute light 

 gray dots posteriorly. This specimen has a few indistinct dorsal and 

 lateral spots, but the main pattern appears on head and neck, where 

 the dark slate-colored supratemporal streak appears, and the irregular 

 dark occipital and nuchal markings are in evidence. No limb bars 



