40. THAMNOPHIS 835 



Description. Head distinct from neck, flat-topped, 

 with narrow, rounded snout, and temporal regions some- 

 times slightly swollen. Eye of moderate size. Rostral 

 large, bounded behind by internasal, anterior nasal, and 

 first labial plates. Plates on top of head: A pair of inter- 

 nasals, a pair of prefrontals, a frontal, supraocular of each 

 side, and a pair of parietals. Anterior and posterior nasals 

 distinct. One loreal. Preoculars usually two, sometimes 

 one, very rarely three. Postoculars normally three, some- 

 times four, very rarely two or one. Temporals normally 

 one, followed by two, sometimes 1+ 3. Superior labials 

 normally eight, rarely seven. Inferior labials normally 

 ten, rarely nine, 1 1 or eight. Usually the fifth, sixth or 

 seventh superior and inferior labials largest, the fourth and 

 fifth or third and fourth superior reaching eye, first pair 

 of inferior meeting on median line. Two pairs of genials, 

 posterior about equal in length to anterior. Scales on body 

 in 21 or very rarely, 19 or 23 rows, all keeled except some- 

 times the first row of each side. Anal plate not divided. 

 Gastrosteges varying in number from 151 to 183, males 

 having from 157 to 183, females from 151 to 176. Uros- 

 teges in two series of from 63 to 97, males having from 76 

 to 97, females from 63 to 91. 



The coloration usually is not different from that of 

 typical Thamnophis ordinoides vagrans, except that the 

 dorso-lateral regions usually are much darker. Because 

 of this, the spots are less evident, but they may usually be 

 made out. The upper lateral spots invade the edges of the 

 dorsal line as in T. o. vagrans. As in that subspecies also 

 the gastrosteges are often marked basally and centrally 

 with black or slate. The dorsal and lateral lines usually 

 are quite distinct. Some specimens, however, are so dark 

 as to conceal the dorsal spots, and one is black everywhere 

 excepting the chin, throat, and a few bits of skin between 



