1901.] NATURAL SCIENCES OF rHILADKLPIIIA. 45 



trals dark red ofteu appears, which usually shows plainly on the 

 chin ; upper labials light, Avith red or blackish margins. This 

 species is one of the largest of North American snakes; in Florida 

 it reaches about 1900 mm. (tail 350), and along the lower Rio 

 Grande, in Texas, it exccds those dimensions. 



Hab. — Georgia and Florida to eastern Texas; northern IMexico. 



COLUBER L. 



Syst. Nat., Ed. X, 216 (1758); Scotoiihis B. and G., I. c, 7:i ; Elaphis 

 (part) D. and B., I. c, VII, 241 ; Coluber Cope, /. c, 630, and liep. 

 Nat. Mus., 825 ; Coluber (part) Boa!., I. c, II, 24. 



Maxillary teeth smooth, equal ; one loreal ; two nasals; two inter- 

 nasals; one preocular; two prefrontals; scales in 19-35 rows; 

 generally more or less keeled, with two pits; anal divided; size 

 moderately large; head distinct. 



Hab. — Northern hemisphere. 



Reliable specific characters, drawn from the scutellation, are want- 

 ing in the American species of Coluber. The proportions of the 

 frontal and parietal plates, upon which some stress has been laid, 

 are so variable with age and in individuals, that little importance 

 can be attached to them singly; except that in vulpinus, and still 

 more in llndhehneri, the anterior border of the frontal is wide and 

 the lateral angles are obtuse, so that the plate is often subtrian- 

 gular. Cope divides the species into sections, according to the 

 number of anterior temporals, but I find them by no means con- 

 stant enough to serve that purpose. The number of veutrals and 

 subcaudals is not diagnostic, the limits of variability overlapping 

 in most species; although quaclrivittatus, a long-tailed species, has 

 the largest number of subcaudals, and vidjnnus, which is short 

 and thick, has the least. There are fairly constant difl^erences in 

 pattern and color, and upon these, with a totality of other charac- 

 ters, they may be divided with some certainty. 



Key to the American Species. 



a. — Scales smooth, or fi to 13 rows weakly keeled: 



Light gray with brown spots, 1. C. emoryi. 



Red with brick-red spots, 2. (7. guttatus. 



Yellow with four brown stripes, . . o. C qxiadrivittaiiis. 

 h. — Scales with 9 to 21 rows more strongly keeled: 

 9-11 rows keeled; yellow with distinct spots, 



4. C. vulpinus. 



9-21 rows keeled; black above, or yellow with spots; lateral 



spots elongated, 5. C. obsoletns. 



