384 THE SNAKES OP FLORIDA. 



inhabited by the 0. d. triangulus is much older geologically than that 

 where the 0. d. coceineus is found, the former is probably the primitive 

 type. 



triangulus 



I 

 clericus 



I 

 collaris 



poh/zonus doliatus annulatus 



occipitalis^^^ ^8ysj)ili<* parallel™ 



^"-■--coicini tt« - »- J ^*"^ 



The geographical distribution of the subspecies is related to their 

 characters. 0. d. coceineus is exclusively a form of the Gulf border, and 

 the 0. d. triangulus is northern, and is not known from south of Wash- 

 ington, D. 0. The other forms in the same series occupy the intermedi- 

 ate latitudes. Thepolyzon us, occipitalis, and annulatus are Mexican, and 

 the 0. d. paraUelus is Floridan. The color increases in brilliancy to the 

 south, as the 0. <l triangulus is brown-spotted, and the 0. <l. coceineus 

 crimson. The size diminishes in general in the same direction, the spe- 

 cies recovering its size in Mexico. 



The characters of the OpMbolus doliatus syspilus are as follows: 



Head small, flattened above, with the snout rounded; neck slightly 

 contracted; body elongated, rather slender : scarlet above, and marked 

 with black rings in pairs ; between each pair is a white ring. 



The head is rather small, flattened above, with the snout rounded ; the 

 vertical plate is pentagonal, with an acute angle behind ; the superior 

 orbitals are oblong quadrilateral, broadest behind, and not projecting 

 over die eye ; the oceipitals are polygonal and very large ; the frontal is 

 broad and pentagonal, narrowest externally, where it descends to join 

 an elongate quadrilateral loreal plate. The anterior frontals are also 

 quadrilateral, smaller than the posterior, and broadest externally. The 

 rostral plate is large, heptagonal, and concave below. There are two 

 nasal plates, the posterior square, the anterior emarginated behind for 

 the nostril, which does not enter the posterior, but comes out at its an- 

 terior border. There is a single anterior orbital plate, oblong, slightly 

 concave behind, and two small, subround, posterior orbitals. The infe- 

 rior wall of the orbit is made up of the third and fourth superior labial 

 plates, of which there are seven. 



The nostrils are lateral, and near the snout. The eyes are small, the 

 iris bright reddish-gray. The neck is but slightly contracted, and is 

 covered with small, smooth, subhexagoual scales. The body is long, 

 tolerably stout, and covered above with scales similar to those of the 

 neck, but larger. The tail is rather short, thick at its root, but soon 

 becomes smaller, and terminates in an acute tip. 



The anterior top of the head is crossed with a black band at the ex- 

 tremities of the oceipitals, and the dark color may extend as far as the 



