112 BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



tends to be more dwarfed, as shown by the reduced number of ventral 

 plates and possibly by a tendency toward 7 instead of 8 superior 

 labials. Its relation to sauritus will be considered later. 



SA URITUSm 



Description. — This is the l)est and longest known form in the 

 group. The lateral stripe is iii)on the third and fourth rows through- 

 out the length of body. The tail is longer than in iwoximus, but not as 

 IcMig as in sacJceni, the length varying from .29 to .36. The scutella- 

 tion may be described as follows: 19-17 dorsal scale rows; 7, occa- 

 sionally 6 or 8, superior labials; 10, occasionally 9, rarely 11, inferior 

 labials; ventral plates, 150 to 172; subcaudal scutes, 87-137. The 

 ground color above is usually chocolate brown, l)ut varies from light 

 oUve l)rown to black. Michigan specimens are quite frequently 

 black, with the exception of the keels of the scales, which are light 

 brown. The stripes are nearly always bright and conspicuous, the 

 dorsal generally having an orange tint, the laterals paler and of a 

 greenish cast. The labials are usually without black blotches and 

 the lateral spots are seldom distinct, although they are not always 

 entirely fused to the total abolition of the light (whitish) interspaces. 

 As in iwoxhnus and saclceni, the ventral spots are generally absent. 



Habits and hahitat relations. — Like the other members of the group, 

 sauritus seems to be more than ordinarily aquatic in its habits, but 

 apparently less so than either proximus or sacJceni. In Michigan 

 we have generally found it about the margin of ponds and streams 

 in damp woods. It is somewhat of a climber, and is occasionally 

 found in bushes, several feet from the ground. When pursued it 

 glides through the pools and herbage at an astonishing rate, and does 

 not hesitate to take to water and conceal itself among the water 

 plants, but it generally remains near the surface, and we have never 

 observed it dive to the bottom like a natricid snake. There are 

 numerous short notes in the literature, to the effect that sauritus 

 prefers damp situations. 



Ditmars (1907, 217-219) states that it feeds on salamanders, tad- 

 poles, frogs, and fish, but, like sacTceni, refuses earthworms. Two 

 other writers, Atkinson (1901, 151) and Surface (1906, 142-143), 

 record insects in stomachs examined. The latter gives the follow- 

 ing as making up the stomach contents of Pennsylvania specimens: 

 Earthworms, spiders, insect fragments, ants, Plethodon cinereus, 

 Spelerpes hilineatus, Hyla versicolor. It should be noted that the 

 insects may have been contained in the stomachs of the frogs and 

 salamanders. The number of young is comparatively small; we 

 have counted the embryos in a few specimens, and they seem to aver- 

 age about a dozen. 



o Thamnophis sauritus (LiNNiEus), Syst. Natur., XII, p. 385. 



