MEXICAN SNAKES AND CROCODILIAN S SMITH 



THAMNOPHIS MACROSTEMMA MEGALOPS (Kcnnicott) 



481 



Seventeen specimens were collected near Progreso, Chihuahua (Nos. 

 104633, 104042-57). 



Table 40. — Variation in Thanmophis macrostemma megalops 



U.S.N.M. 

 No. 



104633 

 104642 

 104646 

 104648 

 104649 

 104650 

 104653 

 104654 

 104643 

 104644 

 104645 

 104647 

 104651 

 104652 

 104655 

 104656 

 104657 



Sex 



9 

 ? 



9 

 9 

 9 

 9 

 9 

 9 

 d" 



& 

 <? 

 c? 



d* 

 d 1 



Scale rows 



21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 

 21-21-17 



Ventrals 



154 

 157 



160 

 160 

 159 

 154 

 161 

 157 

 161 

 167 

 165 

 162 

 166 

 164 

 162 

 171 

 163 



Caudals 



lo 



69 



82 

 82 



81 

 81 



79 + 



Supra- 

 labials 



8-i 



8-9 

 8-8 

 8-8 

 8-8 

 8-8 

 8-8 

 8-8 

 8-8 

 8-8 

 S-? 



Infralabials 



10-10 

 10-11 

 11-11 

 11-11 

 11-11 

 10-11 

 10-11 

 10-11 

 10-11 

 10-10 

 10-10 

 10-10 

 10-10 

 10-11 

 10-? 

 10-10 

 ?_? 



Preoculars 



1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-1 

 1-? 



Postoculars 



3-3 



3-3 

 3-3 

 3-3 

 3-4 

 3-4 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-? 



The Museum has 18 others from Mexico, as follows. Sonora: 

 Santa Magdalena (No. 905 ; Tucson, Ariz. ? ) . Durango : Ada Magda- 

 lena (No. 46366). Chihuahua: Casas Grandes (No. 46377) ; Colonia 

 Garcia (No. 40335) ; Santa Rosalia (No. 40542) ; Sierra Madre (No. 

 40500) ; Chihuahua City (Nos. 14220 [2], 40448) ; "Chihuahua" (Nos. 

 7248, 14258, 14277 [2], 14289 [2], 14292, 45590). Nayarit: ? Santa 

 Teresa (No. 40429). 



THAMNOPHIS MARCIANUS (Baird and Girard) 



Thamnophis marcianus Smith, Zoologica, vol. 27, p. 114, 1842. 



Eight specimens (Nos. 104034-41) were collected near Progreso, 

 Chihuahua. 



The Museum has 20 others from Mexico, as follows : Chihuahua : 

 15 leagues north of Guerrero (No. 40583) ; Ojos del Diablo (No. 30837) . 

 "Sonora": No. 7235. Tamaulipas: Charco Escondido (No. 849); 

 Matamoros (Nos. 15344, 801 [19], 5491) ; 38 miles south of Reynosa 

 (No. 95183). 



