644 NORTH AMERICAN SNAKES COPE. 



Coluber siniHs Liun.,Sy8t. Nafc. Ed., xiii, 1766, p. 216; Gmel. Linu. Syst. Nat. Ed., 



XIII III, 1788, p. 1086. 

 Heterodon 2)latyrhinus Schleg., Ess. Phys. Serp., 1837, p. 97, PI. iii. Figs. 20, 22; Damet 



Bibr., Erp. Gen., vii, 1854, p. 768-772. 



Austroriparian region. 



Heteiodon nasicus Ud. and Gird. 



Cat. Rept. N. Amer., PI. i, Serpents, 1853, p. 61 ; Heterodon simus nasicus Cope, Check 

 List Batr. Rept. N. Amer., 1875, p. 43. 



Frontal and parietal scuta usually wider than long, the parietals often 

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

 strongly recurved. No inferior nasal plate cut off from the postnasal. 

 Two or more loreals. Superior labials eight, all much higher than long. 

 First row of temporals generally four. From three to twenty-four ac- 

 cessory scales beside and behind the azygos plate. Scales in twenty- 

 three rows, all keeled except the first three on each side. Proportions 

 of body more slender than in H. simus. 



Color light yellowish gray above, with a median dorsal series of rather 

 closely placed brown spots, and with two alternating series of brown 

 spots on each side. Three brown, short, longitudinal nuchal brown 

 bands, and a brown band from each eye posteriorly. Belly either en- 

 tirely black or tessellated with black and white. 



This is the western representative of the H. simus, to which it is nearly 

 allied. It can be always distinguished, however, especially in its typi- 

 cal subspecies, by the characters given. A single specimen out of the 

 many in the U. S. National Museum (No. 4961), from Texas, displays an 

 inferior nasal plate. 



Two forms of the R. nasicus inhabit different regions and may be re- 

 garded as subspecies. 



Scales accessory to azygos plate, two or three; loreal small or wanting; belly black 

 and white spotted H. n. kennerhji. 



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

 belly nearly entirely black H. n. nasicus. 



In the H. n-Jiennerlyi in three out of six specimens the parietal scuta 

 are shorter than the frontal. In sixteen of the H. n. nasicus, ten speci- 

 mens have the parietals shorter than the frontal. In the small number 

 of accessory scales the H. n. hennerlyi approaches the H. simus more 

 more nearly does the H. n. nasicus. The same affinity is indicated by 

 the smaller amount of black on the belly. It represents the genus in 

 the Sonoran region, while the H. n. nasicus occupies the central. 



Heterodon nasicus kennerlyi Kennicott. 



Heterodon kennerlyi Kennicott, Proc. Acad. Phila. 1860, p. 336. Heterodon ximns ken- 

 nerlyi Coues tfc Yarrow, Herp. Dak. &, Mont., Bull. U. S. Geol. Snrv. Terrs., 1878, 

 IV, p. 271; Jan, Icon. Gen. Ofid., Livr. 10, PI. v. Fig. 2, 



"Western Texas and Southern Arizona, 



