96 



Key to thk Species of Katrix in the E. U. S., north of Flokida. 



A. Colors ai-ranged in leugthwise stripes; scales iu 19-21 rows. 



a. With a vertebral dark vitta; another ou fifth row of scales; 

 a pale stripe aluug the flanks, and two dark stripes on the 

 middle of the belly. leberis, p. 96. 



aa. With a vertebral light band. 



b. A dark vitta on 1st row, another on 8th; two rows of 

 black dots on middle of the belly. rigicla, Appendix, 

 bb. Dark vittee on 4th and 8th rows ; belly uniform yellow. 



grahamii, Apjoendix. 

 bbb. Dark vitt?e on 2d and 3d, and on 5th and 6th rows; ab- 

 domen with two clouded bauds on yellow ground. 

 Texas. clarkii. 



AA, Colors arranged in form of blotches; scales in 19 to 33 rows. 



c. Scales in 19-21 rows. kirtlandii, p. 97. 



cc. Scales in 23-25 rows. 



d. Auteorbitals 1 ; upper labials 8. . sipedon, p. 98. 



dd. Auteorbitals 2 ; upper labials 9. Washington, D. C. 



bisecta, 

 ccc. Scales in 27-33 rows. 



e. Scales in 27 rows ; 3 alternating rows of square spots. 



rhovibifera, p. 101. 



ee. Scales in 27-29 rows ; a row of small plates between the 



eyes and the upper labials. cyclopion. Appendix. 



cccc. Scales in 31-33 rows. Maryland to Florida. taxispilota. 



Natrix leberis, (Linn.). 

 Leather-snake. 



Coluber Ze6em,Linua3US, 1758, 6'.^, ed. x, 216 ; Tropidonolus leberis, Hol- 

 brook, 1842, 54, iv, 49, pi. 13 ; Garman, 1883, IS, 27, pi. 2, fig. 1 ; 

 Recjma leberis, Baird & Girard, 1853, G, 45; Natrix leberis, Cope, 1892,. 

 3, 668. 



Head rather small, not much broader than the neck; somewhat de- 

 pressed. Nasals 2, sometimes not well separated. Auteorbitals and 

 postorbitals each 2. Upper labials 8, the 5th and 6th largest, the eye 

 over 3d and 4th. Lower labials 10, the 5th and 6th largest. Scales dis- 

 posed in 19 rows; all distinctly keeled, giving the snake a rough appear- 

 ance. Ventrals 140 to 151. Pairs of subcaudals 64 to 86. Tail forming 

 about one-fourth the total length. 



The color above varies from olive brown to chestnut brown. There is^ 

 a vertebral dark stripe occupying the median row of scales,^ and another 



