LIST OF ILLUSTRATIONS. XI 



Fig. 49. Diagram showing the variation in the proportionate tail length in 



Thamnophis sauritus 116 



50. Diagram showing the variation in the number of siil)caudal scutes in 



Thamnophis sauritus 117 



51. Phylogenetic development of the Sauritus group 119 



52. Distribution of Thamnophis angustirostris, as indicated by the locality 



records 122 



53. Distribution of Thamnophis angustirostris melanogaster, as indicated 



by the locality records 126 



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



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



about 20 miles east of Los Angeles, California. (Photograph by 

 William L. Finley ) 134 



56. Distribution of Thamnophis liammondi, as indicated by the locality 



records I35 



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



yiophis hammondi 136 



58. Habitat of Thamnophis ordinoides elegans. Klamath marshes, south- 



ern Oregon. (Photograph by Finley and Bohlman) 139 



59. Distribution of Thamnophis ordinoides elegans, as indicated In- the 



locality records 142 



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



nophis ordinoides elegans I43 



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



nophis ordinoides elegans I44 



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



records 15q 



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



nophis ordinoides I5I 



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



Thamnophis ordinoides I53 



65. Diagram showing the variation in the number of infralal)ials in Tham- 



nophis ordinoides I53 



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



Thamnophis ordinoides ; I54 



67. Diagram showing the variation in the numljer of subcaudal scutes in 



Thanmophis ordinoides I54 



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



nophis ordinoides 155 



69. Phylogenetic development of the Elegans group 158 



70. Distribution of Thamnophis ecpies, as indicated by the locality records. 161 



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



nophis eques ■ jgg 



72. Diagram showing the variation in the number of supralaliials in Tham- 



nophis eques 2g3 



73. Distribution of TJiamnophis sirtalis parietalis, as indicated l)y the 



locality records Igg 



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



nophis sirtalis parietalis from Montana 170 



75. Variation in the number of infralal^ials in 20 specimens of Thamnophis 



sirtalis parietalis from Montana 170 



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



locality records '_ _ _ jy^ 



