772 



REPORT OF NATIONAL MUSEUM, 1898. 



rostral separated from the prefrontals by two or three small plates, and 

 the azygos entirely cut ott' from the internasals by intervening plates. 

 The lower wall of the nostril is constituted by two small plates; there 

 is a second small plate above the loreal; in fact, a general tendency to 

 break up into small plates. The markings on the back are restricted 

 to a dorsal series, with a dusky shade opposite, and a lateral series 

 opposite the light yellowish intervals; the ground color of the sides a 

 quite uniform yellowish brown. Specimens from Mississij^pi have the 

 dorsal spot smaller and nearly circular. 



This is the most robust and the shortest species of the genus. Its 

 range is the Austroriparian region, omitting western Texas, where the 

 H. nasicus replaces it. 



Heterodon simus Linnceus. 



\ 



HETERODON NASICUS Baird and Girard. 



Heterodon nasicus Baikd and Girard, Cat. N. Amer. Rept., Pt. 1, Serp., 1853, p. 61. 

 Heterodon simus nasicus Cope, Clieck-list N. Amer. Batr. Rept., 1875, p. 43. 



Frontal and parietal scuta usually wider thau long, the parietals 

 often shorter than the frontal. Head short ; rostral plate very large 

 and strongly recurved. No inferior nasal i)late cut off from the post- 

 nasal. Two or more loreals. Inferior labials* eight, all much higher 

 than long. First row of temporals generally four. From tliree to 

 twenty-four accessory scales beside and behind the azygous plate. 

 Scales in twenty-three rows, all keeled except the first three on each 

 side. Proportions of body more slender than in IT. ,simus. 



Color light yellowish-gray above, with a medium dorsal series of 

 rather closely jjlaced brown spots and with two alternating series of 

 brown spots on each side. Three brown short longitudinal nuchal 

 brown bauds and a brown band from each eye posteriorly. Belly 

 either entirely blaf^k cr tessellated with black and white. 



Tliis is the Western representative of the H. simvs, to which it is 

 nearly allied. It can be always distinguished, however, especially in 

 its typical subsj^ecies, by the characters given. A single si^ecimen out 

 of tlie many in the U. S. National Museum (Cat. No. 4961) from Texas 

 displays an inferior nasal plate. 



Two forms of the H. nasicus inhabit different regions and maybe 

 regarded as subspecies. 



Scales accessory to azygous plate two or three ; loreal small or wauting ; belly black 

 and white spotted H. n. Jcennerlyi. 



Scales accessory to azygous plate from eight to twenty-four; loreals generally two; 

 belly nearly entirely black H. n. nasicus. 



