VARIATIONS OF GARTER-SNAKES. 11 



When the spots on the skin are generally fused, those on the scales 

 are either wanting or represented in narrow broken bands along the 

 stripes, as mentioned above. When, however, the latter show a 

 tendency to form cross-bars, the spots on the skin exlii})it the same 

 arrangement. Practically always, however, the first spot of the two 

 rows above the lateral stripe fuses with its neighbor to form a large 

 nuchal blotch, which may or may not be distinct on the scales. 

 These blotches ma}^ cross the lateral stripe and fuse with the cor- 

 responding spot on the first row of scales, and in one section of the 

 genus (the Sirtalis group) are frequently followed by one to five 

 similar blotches which are likewise formed by the fusion of the 

 spots of the second and third rows. The color of the skin in the 

 interspaces is usually white or very light ])luish or greenish, but it 

 ma_v also be j^ellowish or red, and tl^ color of the interspaces usually 

 encroaches to a varying degree upon the involved scales. 



The stripes are typically three in number, consisting of a dorsal 

 which involves the median and usually a varying amount of the adja- 

 cent rows, and a lateral on either side situated on the second and third, 

 third, third and fourth, or second, third, and fourth rows from the 

 bell3^ The color of these stripes is usually brighter than the ground 

 color, being white, various shades of blue, green, or yellow, or occa- 

 sionally red. The laterals, while frequently narrow, usually involve 

 two rows of scales. In one form (butleri) they cover part of three 

 rows, while in another {marcianus) they are, for most of the length, 

 on one only. In only two forms (angustirostris , sumichrasti) are they 

 characteristically obsolete. The dorsal stripe, on the other hand, 

 varies in width from one to five or six rows and is more often lacking. 

 Neither the dorsal or laterals are absent individually except in 

 melanistic specimens, being very constant in the forms which possess 

 them. 



The head is usually of the same color above as the ground color of 

 the back, but it is often more olive or brownish, and is occasionally 

 marked with red or black. There are nearly always two proximate 

 bright spots upon the parietal plates, although these are occasionally 

 absent in individuals irrespective of race. On the sides of the head 

 the dark color of the upper surface meets the usually much lighter 

 color of the superior labials, into which it grades on the preoculars, 

 postoculars, and temporals. The labials are as a rule much lighter 

 than above, the color being varying shades of green, yellow, blue, or 

 occasionally white. They are nearly always more or less margined 

 with darker, and there is a tendency, more pronounced in some forms 

 than in others, for one of these dark margins to be extended iq)ward 

 along the anterior margin of the preoculars, and one along the pos- 

 terior margin of the postoculars, making a conspicuous pattern on 

 the sides of the head. 



