LIST OF ILLrSTRATIONS. XI 



Fio. 49. Diagram t;howing the \ariali()ii in the proportionate tail lengtli in 



'I'hamnophis saurit U8 1 J 6 



50. Diagram showing the variation in the numhei- of snlxauchvl scutes in 



Thamnophis sanritus 117 



51. Phylogenetic deveh)pment of the Sanritus group 1J9 



52. Distril)ution of Thamnophis angustirostris, as indicated l)y the locality 



records 122 



53. Distribution of Thamnophis angustirostris melanogaster, as indicated 



by the locality records 126 



54. Distribution of Thamnophis scalaris, as indicated liy the locality records. 128 



55. Habitat of Thamnophis hammondi. Stream at Baldwin's rancli, 



al)0ut 20 miles east of Los Angeles, California. (Photograph l)y 

 William I.. Finley i 134 



56. Distribution of Tliamnojjhis hammondi, as indicated l)y the locality 



records 135 



57. Diagram showing the variation in the number of preoculars in Tham- 



nophis hammondi 136 



58. Habitat of Thamnophis ordinoides elegans. Klamath marslies. south- 



ern Oregon. (Photograph by Finley and Bohlman) 139 



59. Distribution of Thamnophis ordinoides elegans, as indicated by the 



locality records 142 



60. Diagram show^ing the variation in the dorsal scale formula in Tham- 



nophis ordinoides elegans 143 



61. Diagram showing the variation in the number of preoculars in Tham- 



nophis ordinoides elegans 144 



62. Distribution of Thamnophis ordinoides, as indicated by tlie locality 



records 1.50 



63. Diagram showing the variation in the dorsal scale formula in Tham- 



nophis ordinoides 151 



64. Diagram showing the variation in the number of supralalnals in 



Thamnophis ordinoides 153 



65. Diagram showing the variation in the number of infralabials in Tham- 



nophis ordinoides 153 



66. Diagram showing the variation in the Tiumber of ventral scutes in 



Thamnophis ordinoides 154 



67. Diagram showing the variation in the numl)er of subcaudal scutes in 



Thamnophis ordinoides 154 



68. Diagram showing the variation in the number of preoculars in Tham- 



nophis ordinoides 1,55 



69. Phylogenetic development of the Elegans group 158 



70. Distril)ution of Thamnophis eques, as indicated by the localit y records. 161 



71. Diagram showing the variation in the donsal scale formula in Tham- 



nophis eques 1(53 



72. Diagram showing the variation in the number of supralal)ials in Tham- 



nophis eques 1(53 



73. Distril)ution of Thamnophis sirtalis parietalis, as indicated by the 



locality records 109 



74. Variation in the number of supralabials in 20 specimens of Tham- 



nophis sirtalis parietalis from Montana 170 



75. Variation in the number of infralabials in 20 specimens of Thamnophis 



sirtalis parietalis from Montana 170 



76. Distribution of Thamnophis sirtalis concinnus, as indicated by the 



locality records 174 



