CROCODILIANiS, LIZARDS, AND f?NAKES. 371 



it to the insertiou of the hind leg. The male also has the eutire under 

 surface of the head black, with a large blue patch behind. The throat 

 and sides of neck, from the lateral fold to and along the anterior face 

 of the arm, are black. There is a large blue patch on each side of the 

 belly from (but not in) the axilla? to the groin. This is black internally, 

 where the shape is elliptical, the two of opposite sides separated when 

 nearest by about two scales. In the groin the color is chiefly black, 

 and this sometimes covers the whole anterior surface of the thigh and 

 the preanal region. The black along the belly is sometimes confluent 

 with that anterior to the arm, but there is usually an interruption con- 

 necting the grayish of the thoracic region with that of the inner surface 

 of the arm, and i)rodu(dug a distinct cross. The scales on the under 

 surface, where not colored as described, are white, finely punctate with 

 black, producing a grayish appearance. This mottling is sometimes 

 aggregated into distinct short lines, most conspicuous in the female. 

 The head has some transverse dark lines above. 



In the female the sides sometimes appear spotted with whitish, from the 

 tips, single scales being of this color. There is occasionally a trace of blue 

 on the chin and sides, and generally of black at the insertion of the arm. 



The shade of coloration varies considerably, l)eing sometimes so dark 

 as entirely to obscure the markings. The tip of the chin in the ntale 

 is sometimes greenish white when not very highly colored; in fact, this 

 is most generally the case. 



Many specimens exhibit a series of dusky lines about the»head, among 

 them two or three crossing the upper part, the median one opposite the 

 center of the eyes. There are also usually two lines backward from the 

 posterior canthus, one directed toward the occiput, the other crossing 

 the upper end of the car and confluent with the dusky of the sides. 



Professor Baird distinguished the Pacific slope representatives of 

 this species as a species under the name of S. oecidentalis Baird. He 

 states the difference from Eastern specimens to be as follows: 



The first positive difference is seeu in the greater roughness of the dorsal and lat- 

 eral scales, owing to the greater prominence of the keels of each scale. Each scale 

 is more elongated and pointed owing to the greater prominence and haikward exten- 

 sion of the mncro, and the edges on each side the spine have two distinct serrations 

 instead of scarcely any. On the other hand, however, the belly scales are many 

 entirely without notch, and this where present is always very slight or obsolete, 

 while in undulatus one or more are seen distinct and angular in every scale; a dif- 

 ference which appears to be constant consists in the entire smoothness of the scales 

 on the inner or under surface of the tibial joint, and those on the under surface of 

 the tail for a distance behind the anus nearly equal to the length of the head. The 

 posterior edge of these scales is angular or truncate, without any mucro, and with 

 or without a median notch. In S. undulatus the scales on the under side of the tibia 

 are all distinctly carinated, mucronated, and with lateral notches, those behind the 

 anus being similarly constituted except one or two first rows. The plates under 

 the cliiii are decidedly smaller and more numeroiis. Those on the back appear 

 smaller likewise. 



The colors are so very similar that with the materials before nie I can scarcely 

 indicate any constant difference. The colors appear rather darker, and the legs of 



