Vol. VIII] VAN DENBURGH AND SLEVIN— GARTER-SNAKES 255 



Remarks. — Garter-snakes from the San Joaquin Valley and 

 Lower Sierra Nevada have been referred usually to T. vagrans 

 or T. hammondii. This has never been satisfactory, for, 

 although the San Joaquin snakes resemble both these sub- 

 species, they are not like typical specimens of either, but rather 

 may be said to combine characters of both. Certain specimens 

 resemble T. o. hammondii rather closely, but the presence of a 

 dorsal line on at least a portion of the neck will usually serve to 

 distinguish them from that form. Sometimes the line is con- 

 tinued along the back, but it often is very indistinct. The gas- 

 trosteges seem to be somewhat more numerous than in T. o. 

 hammondii, and a similar tendency is apparent in the infra- 

 labials, which often are eleven instead of ten. On the other 

 hand, two preoculars are found much less frequently than in 

 T. 0. hammondii. Intergradation between these two subspecies 

 is shown by certain specimens from the San Joaquin Valley, 

 but seems to be individual rather than geographic. It doubt- 

 less will become more evidently geographic when specimens are 

 secured from the proper areas. 



The relationship of T. a. couchii to T. o. vagrans is still 

 closer than to T. a. hammondii. This is shown by the charac- 

 ter of the spotting adjacent to the dorsal line when present, the 

 frequent occurrence of more or less dark pigment on the gas- 

 trosteges, and the fact that in many of the specimens of T. o. 

 couchii some indication of a dorsal line is present. 



In typical T. o. vagrans, as it occurs in Idaho, Utah and 

 eastern Nevada, the dorsal line is well marked, the dorsal spots 

 are very evident and invade the edges of the dorsal line, and the 

 gastrosteges almost always are rather heavily pigmented. T. o. 

 couchii differs from this type of coloration in the shortness or 

 indistinctness of its dorsal line, which may be only a half-inch 

 in length, in the less frequent and less extensive pigmentation 

 of the gastrosteges, and in the absence, indefiniteness, or less 

 characteristic arrangement of the dorsal spots. Intergradation 

 between T. o. couchii and T. o. vagrans is to be looked for in 

 western Nevada. 



The relationship between T. o. couchii and T. o. elegans also 

 is very close. Typical T. o. elegans seems to occur only at 

 considerable elevations in the Sierra Nevada and in the moun- 

 tains of southern California. T. o. couchii occupies the lower 



