188 BULLETIN 17 5, UNITED STATES NATIONAL MUSEUM 



or less distinct longitudinal stripe at the level of the second and third 

 and fourth lateral series of spots. The belly bears a series of small 

 dark spots at each side, which are rarely more than one-half to one 

 scale in length and are separated by 1 to 4 scutes. On some speci- 

 mens these spots are rather pale and indistinct. In addition to the 

 lateral series of spots the belly may have numerous brownish or black 

 spots scattered irregularly over the posterior part, or even throughout 

 the entire length, but is more often merely dotted with minute dark 

 specks, or is immaculate. The top of the head is pale brown, occa- 

 sionally somewhat dappled with darker brown, and frequently with 

 the suggestion of a dark transverse band crossing the top of the head 

 from the supralabials underlying the eyes, over the anterior part ol 

 the supraoculars and frontal, and the posterior part of the prefrontals. 

 On each side a dark band from the eye to the posterior angle of the 

 jaw also is frequently apparent. The tliroat is white. (Fig. 64, c.) 



Variation. — In the accompanying graphs representing geographic 

 variation in the form, the range has been divided into regions that 

 are numbered from south to north along the abscissas of the graphs 

 as follows: 



Region 1. San Jose del Cabo, Lower California. 



2. Northern part of Lower California. 



3. San Diego County, Calif. 



4. Riverside, Los Angeles, and San Bernardino Counties. Calif. 



5. Ventura, San Luis Obispo, and Santa Barbara Counties, Calif. 



6. Monterey and Santa Cruz Counties, Calif. 



7. San Martin Island, Lower California. 



8. South Coronado Island, Lower California. 



The island specimens have been graphed as separate units, since 

 they cannot logically be inserted at any point in such a geographic 

 series. Although the small numbers of specimens from the southern 

 and northern extremes of the range and from the islands of San Martin 

 and South Coronado render the conclusions drawn in regard to those 

 regions of slight value, nevertheless certain general variational tend- 

 encies appear to exist in correlation with the geographic distribution 

 of the form. In regard to the island specimens, it will be noted that 

 the scale rows of the South Coronado specimens are markedly high 

 (fig. 79), although well within the range of variation for the group 

 as a whole, and thus perhaps the specimens under consideration 

 represent an extreme of variation for that region. The numbers of 

 both body and tail spots appear to be low in both the San Martin 

 and the South Coronado specimens (fig. 84), but here again the small 

 number of specimens necessitates extreme caution in the interpreta- 

 tion of the data. In the numbers of scale rows (fig. 79), ventrals 

 (fig. 80), and infralabials (fig. 82) there seems to be a general tendency 

 toward a slight decrease from south to north, which is most marked 

 in the case of the ventrals. The remaining scale characters (fig. 81), 



