No. 50.] 115 



itarmless and exceedingly inoffensive, notwithstanding its threatening ap- 

 pearance when flattening the head and body, and emitting a succession of 

 hisses, similar, on a very small scale, to an engine letting off steam. To those 

 familiar with the habits of this species in making these sibilant sounds, the 

 question mooted in the papers, some years since, appeared supremely ridicu- 

 lous, in view of the grave assertions to the contrary by some of the disputants. 

 It is found throughout the United States, though scarcely extending far 

 beyond the Missouri river. 



Cenus SCOTOPHIS, Baird & Girard. 



G-EN. GhaR. Form eolubrine. Body cylindrical, very long ; many indivi- 

 duals attaining a very large size, perhaps the lai^est of all North- 

 American serpents. Head elongated, rather narrow. Vertical plate very 

 broad, sometimes wider than long. Posterior frontals very large. Post- 

 orbitals 2 : anteorbitals 1, generally very large ; the longitudinal ex- 

 tension of this, and of the postfrontals, producing a much elongated 

 muzzle- Mouth deeply cleft ; outline nearly straight. Dorsal rows of 

 scales 23 — 29 : those along the back slightly carinated (9 - 15 rows) ; 

 on the sides, smooth. Abdominal scutella) from 200 to 235 ; posterior 

 bifid : subeaudals all bifid. 

 Color brown or black, in quadrate blotches on the back and on the sides, 

 separated by lighter intervals. Abdomen usually coarsely blotched with 

 darker. In one species, dark stripes on a light ground. Although very 

 large and powerful, many of the species of the genus are characterized by 

 their extreme gentleness, rarely become enraged even when provoked. 



Syn. Scotophis, B. & G. 1. c. (1853), 73. 



9. Scotophis alleghaniensis, B. <f- G. — Mountain Blacksnake. 



Spec. Char. Vertical plate longer than broad. Posterior upper labial largest. Out6r 

 7 rows of scales sniooth : dorsal rows 27. Abdominal scutellse 235. Color black; 

 below, mottled anteriorly witli white. White edges to some scales, imparting an 

 appearance of dorsal and lateral blotches, especially in the young. 234-f 1, 86, 

 27; 59i lOf (Penn.). 



