REVISION OF THE KING SNAKES. 133 



their living chiefly above ground. But it appears that this is largely 

 a burro\\dng form. Certain degenerative tendencies may therefore 

 be expected. The infralabials furnish one instance, the averages for 

 which, although admittedly based on a very inadequate number of 

 specimens, can hardly be without significance. This decrease in 

 number of infralabials is probably to be correlated with a shortening 

 of the snout, and the latter is very likely associated wdth burrowing 

 habits. One of the characteristic differences between this form and 

 caUigaster is the shorter and blunter snout, a difference that may 

 usually be observed but that is not easy to measure. 



The number of specimens is too small to reveal geographic tend- 

 encies in the number of scale rows, but, for comparison with the 

 condition in caUigaster, it should be noted that along with the dis- 

 tinctive difference in numbers of labials and the somewhat smaller 

 average size of body, there is a decided decrease in scale formula, 

 an average difference of two rows on each side of the body. 



A sexual difference in scale formula is fairly evident. The figures 

 in the table may be summarized as follows: (1) About half of the 

 individuals of each sex have the formula 21-19; (2) nearly all the 

 rest of the females have a higher foiinula, 21-23-21-19 (one of those 

 having the formula 19-21-19, U.S.N.M. no. 17444, is a highly 

 aberrant individual in other matters of scalation), and most of the 

 males have a lower; (3) no female has 17 rows at the end, while this 

 is the case with about one-fourth of the males. 



In pattern as well as in scutellation and proportions, this form shows 

 itself to be a reduced caUigaster. Moreover, the differences are but 

 slight. The markings on the head are in every way similar, but 

 are less well defined. The smaller average number of dorsal blotches 

 may be accounted for by the shortening of the tail, but these blotches 

 are different in shape. Their anterior and posterior borders are 

 generally slightly convex, instead of concave, as in caUigaster, and 

 they taper nearly to a point on the sides, instead of being truncate 

 or blunt, as in the latter form. The fact that they extend down on 

 the sides commonly to the fifth row of scales instead of to the seventh 

 or sixth is due to the loss of one or two rows on each side of the body. 

 This lower extension of the dorsal blotches may account for the fact 

 that the two lateral series of alternating spots, characteristic of 

 caUigaster, tend to fuse into a single series. Degeneracy is indi- 

 cated by the contracted and transversely zigzag shapes that tliis 

 lateral series assumes. Then, too, the tendency for the pattern to 

 be indistinct seems to be an accentuation of the condition illustrated 

 by the caUigaster of the region from eastern Missouri to Indiana. 



All the differences between rhomhomaculata and caUigaster are 

 traceable to reduction or degeneration and not to any further de- 

 velopment of the characteristics of the latter form. 



