170 BULLETIN 15 4, UNITED STATES NATIONAL MI^SEUM 



Van Dt'nbur<rli {li)±2, p. 492) admitted that the throat of stej- 

 negei'i is sometimes slightly suffused AA'ith gYny or slate, and in the 

 discussion of w.vndui^, lie stated that the central gular and collar 

 scales were a Uttle smaller than those of ste'jnegerl and that the small, 

 smooth, convex granules on the back were usually slightly larger 

 than in that foi-m. 



After the examination of hundreds of specimens of tessclldtus 

 from the west, it seems remarkable to the writer that stejnegerl and 

 mnndus should liave remained as distinct forms up to the present 

 time. The amount of spotting on the throat not only varies with 

 age and individuals, but probably with sex as well. The specimens 

 with the most concentration of black on the throats and at the sides 

 of the head are usually old males. The individual variation is so 

 great in most regions that it is almost certain that in a large series 

 both mundus and sfejnegeri can, be easily found. An attempt to 

 confine this " intergradation " proved so futile during the early part 

 of this study that it was abandoned. The great overlap in colora- 

 tional features and tlie failure of the distinctions based on scalation 

 (as indicated above) render mundus a synonym of stejnegen. 



It seems worth while to discuss the variation found in a series 

 of 94 specimens (from many localities) in the collection of the Cali- 

 fornia Academy of Sciences that was labeled '' stejnegeri '- by Van 

 Denburgh. It was found that the coloration of the breast, abdom- 

 inal region, under parts of the tail, throat and sides of the head, 

 varied greatly. In the majority of the s]iecimens the blackness of 

 the breast, gular region, and sides of the head is confined to small 

 areas (.scattered spots oi- patches) of intense bhu'k. In only a mi- 

 nority of specimens is the truly supposed condition of stej)iege)'t 

 reached. In these the black concentrations are large and prominent, 

 and the breast, throat and sides of the head are well marked Avith 

 contrasting black and white. In some, the abdomen and under 

 surfaces of the hind limbs are covered by black concentrations which 

 fade to slate in other specimens. These markings are always some- 

 what lighter in shade than those anteriorly. Very few of the speci- 

 mens are striped, although some trace of longitudinal arrangement 

 of the dorsal markings is nearly always present. A specimen was 

 found with only vestiges of stripes (C.A.S. No. 40276). 



The practical impossibility of separating sfejnegeri and figris 

 (= tessellatus) has already been discussed. That there is a transi- 

 tion from a brownish to a blackish dorsal color pattern when whip- 

 tails leave the desert is not denied, but the fact that this transition 

 is general, i-atliei- than local, has been ])ointed out. Thus, from the 

 standpoint of tlieir chaiacteristics, certain specimens representing 

 the grahmnii of Texas, the fessellatus of Chihuahua, and the stej- 

 negeri of the west coast are the same, and examples not unlike these 



