...although I wouldn't go so far as to call Thamnophis rear "fanged". I agree that they have large rear teeth but I don't think they qualify as "fangs" (hollow or grooved). Both Thamnophis and Nerodia definitely have some sort of mild irritant and anticoagulant in their saliva. On another note, the genera Elaphe, Pituophis, Lampropeltis, and a few of the related genera completely lack Duvernoy's Glands and so are uncapable of producing toxic saliva. This is one of the few groups of colubrids in the world that have this characteristic. Interesting, huh?