66 BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



of the involved scales. The stripes are ver,y light yellow; the lateral 

 stripe on the third row only anteriorly, and posteriorly on the second 

 and third; the dorsal on the median and about one-half of the adjacent 

 rows encroached on to the median row by the upper row of spots. 

 Large nuchal blotches and a distinct postoral crescent. Head dark 

 olive; first, second, third, seventh, and eighth supralabials olivaceous, 

 the fourth, fifth, and sixth, with the preoculars and second and third 

 postoculars, being light yellow. The tliird, fourth, fifth, and sixth 

 supralabials margined with black. Belly light yellowish ash. In 

 older specimens the ground color becomes darker, and the spots seem 

 to retreat from the scales, although still distinct on the skin. The 

 spots below the lateral stripe also become indefinite, but the stripes 

 themselves retain their position. This variation, however, is appar- 

 ently due to age, as we have said, and as far as we have been able to 

 see there is no marked geograpliic differences in color. 



Affinities. — Considered in the totality of its characters, marcianus 

 stands out in decided contrast to the other forms in this region, and, 

 as we have stated before, this individuality has in great part delivered 

 it from the confusion that has resulted in the efforts to classify many 

 of the other forms. The attempts that have been made to determine 

 the relationships of marcianus have, however, led to several extraor- 

 dinary results. It was described in 1853 by Baird and Girard (1853, 

 36-37) as a distinct species and no attempt was made to establish its 

 affinities for tliirty years. In 1883 Garman (1883, 25 and 138) 

 included it as a subspecies of sirtalis, wliich, however, means little as 

 regards genetic relationships, for we find this writer including as 

 varieties under this species such divergent forms as radix, elegans, and 

 sirtalis. Cope in 1892 (1892, 656) reduced it to the rank of a variety 

 in the Elegans group, on the basis of the position of the lateral stripe 

 on the second and third rows, and the possession of 21 scale rows and 

 8 upper labials, thus allying it to elegans and hammondi. Tliis 

 arrangement was followed by Brown in 1901 in liis review of the genus 

 (1901), but in 1904 (1904, 470) he changed liis mind and derived it 

 directly from jMrietalis, with no explanation as to liis reasons for so 

 doing. These dispositions of the form are uilsatisfactory, to say the 

 least. 



It will be observed that the placing of marcianus in the Elegans 

 group rested upon the assumptions that the lateral stripe is to be 

 considered on the second and third rows of scales, which is far from 

 established, and that racial affinities are indicated by similarity in 

 the number of scale rows. The latter, as we have seen, is also far 

 from being the case, and we are thus freed from the necessity of 

 accepting any of the solutions of the problem that have l)een based 

 on these grounds. We must search for similarities with other forms 



