CROCODILIAXS, LIZARDS, AND SNAKES. GST 



tion, and tliat tlie farther north tlie more is this restricted to the pri- 

 mary pattern. 



Furthermore, it is probable, or even almost certain, that the females 

 retain their stripes and other markings longer than the males, and 

 have a much less tendency, if they exhibit it at all, to reddening and 

 widening of the head, whicli would explain the difterences in size of 

 si)ecimens otherwise similarly colored. It is almost certain that females 

 never entirely lose their stripes and never assume the very wide head. 

 A series (Cat. No. 4137) of three from Tyree Springs, Tennessee, though 

 evidently the same species and of the same size (body and head nearly 

 4 inches) represents very fairly the so-called P. erythrocephalus and 

 quinqueUneatns^ the former being males, the latter female. As far as 

 I have made anatomical examination, all the largest specimens (head 

 "and body 4 inches) of those with narrow head and distinct stripes (as 

 Cat. No. 4130) are females; all those of same or even less size, with 

 very broad, red head and obscure markings (as Cat. No. 4138) are males, 

 and T have no doubt this may be taken as a rule in the present case. 



A figure of the details of the female is No. 3. page 177, of this book. 

 The specimen is from Florida. 



The most northern, as at the same time the smallest, specimens having 

 more the character of P. laticeps or erythrocephaluii tlian that of the 

 others, is in bottle Cat. No. 3150, Irom Carlisle. The head and body of 

 these barely measure 3 inches, and they were captured by myself in the 

 same locality and at the same time with others of the same size agree- 

 ing with S. quinquclineatns. The former are males, the latter females, 

 as shown by actual examination. 



The Plestiodon vittigerum of Hallowell from Michigan' belongs to the 

 middle stage of this species, yar. poJi/f/rammus. In a large nunjber of 

 small skinks with median white line before me there is one which, in 

 most respects like the small blue skinks, differs in having the fine bluish 

 white lines on a black ground very narrow; the hind legs uniform 

 black without any stripe. There is a third lateral stripe on each side, 

 between the fore and hind legs, less distinct than the other, and a 

 short light stripe on each side the median one on the back of the neck. 

 This is along the adjacent edges of the first and second row of scales 

 from the median line, the inner edge of this first row involved in the 

 median stripe. The posterior extremity of the oval light outline on 

 the head above, instead of being connected with the end of the dorsal 

 stripe as its bifurcation, has the two branches curved outward, as a 

 quarter circle, and connecting with the two sui)plementary short cer- 

 vical stripes and not at all with the median. The belly is bluish, 

 becoming white on the under surface of head; tlie rostral i)late and 

 sides of head anterior to the eye are white. 



I do not venture, in the absence of more specimens, to consider this 

 as a distinct species; it, however, is markedly different in the character 



' Proc. Acad. Nat. Sci. Phila., VIII. 1S56. ]>. 310. 



