VARIATIONS 0¥ GARTER-SNAKES. 171 



and halves of the adjacent rows. Such specimens are characterized 

 only by the slight excess of black pigment. We have seen this color 

 phase only in specimens from western Montana (Fort Benton, Flat- 

 head Lake, Three Forks, Bitter Root Valley) and the west slope of 

 the Rocky Mountains in southern British Columbia. It was princi- 

 pally on parietalis specimens of this type that E. sirtalis trilineata 

 Cope (1892, 665) was based, but the characters are not sufficient to 

 warrant the separation of these specimens from ixirietalis. They are 

 indistinguishable from some specimens of concinnus (see p. 176). 



(2) Quite often in typical parietalis specimens the red pigment of 

 the interspaces shows a tendency to encroach upon the black areas, 

 particularly between the fifth, sixth, and seventh scale rows, to the 

 partial or total separation of the lower row of spots from the upper 

 black band. This is not at all remarkable, since it is these scale rows 

 which mark the limits of the spots in garter-snakes which have the 

 two rows distinct. In two specimens from Pitt River, California 

 (Cat. Nos. 21383 and 21384, U.S.N.M.), the separation of the two 

 rows of spots is complete, and a further modification exists in the 

 fact that the lower row of spots, like the upper, has also fused into a 

 longitudinal black band. These specimens have been described as 

 E. sirtalis tetrataenia Cope (Yarrow, 1875, 546), but they are, in my 

 judgment, evidently only two anomalous specimens of parietalis, and 

 this conclusion is supported by the fact that in one of these specimens 

 (No. 21383) the lower black stripe is partially broken up into spots. 

 A similar pattern is occasionally exhibited by concinnus (see p. 176). 



(3) A number of specimens of parietalis from Kansas and Minnesota 

 examined have the first few spots anteriorly fused into transverse 

 blotches between the stripes, as in some Illinois specimens of sirtalis 

 described by Cope as Eutaenia sirtalis semifasciata, and in the eques 

 specimens described by him under the name ocellata. This is merely 

 an individual variation, but may have some significance (see p. 173). 



(4) By far the most significant variation exhibited by parietalis is 

 the breaking up of the lateral black band into the usual upper row of 

 spots. If this alone takes place the result is a coloration practically 

 the same as that of eques and sirtalis, except that the interspaces are 

 red. We have seen this color phase in Colorado (Greeley) and eastern 

 Kansas (Onaga) and Isle Royale, Michigan, specimens, but it can only 

 be certainly determined in fresh material, for the red of the interspaces 

 fades rapidly in preserved specimens, so that they can not with cer- 

 tainty be distinguished from eques (when there are 8 supralabials) and 

 sirtalis, the more so that the modification seems to occur only near the 

 ranges of these forms. 



In Minnesota, eastern Iowa, and Missouri the proportion of speci- 

 mens with two distinct rows of spots is large, and the specimens from 

 this region are further characterized by the frequent absence of red 

 pigment on the sides, a character which is also occasionally found in 



