CKOCODILIANS, LIZARDS, AND SNAKES. 743 



DIADOPHIS Baird and Girard. 



Diadophis Baird and Girard, Cat. N. Amer. Kept., Ft. 1, Serpents, 185.3, p. 112. — 

 Cope, Bull. U. S. Nat. Mus., No. 32, 1887, pp. 54-80. 



Head uonual, distinct from body. Teeth of maxillary bone subequal 

 and in an uninterrupted series. Palatine teeth present. Cephalic plates 

 normal; rostral normal; two nasals; one loreal. Scales smooth, unifos- 

 .sate. Anal i)late and subcaudal scuta divided. Hemipenis simple, with 

 numerous simple calyces and numerous spines. 



Diadophis is allied to Dromieus, but in that genus the last sui)erior 

 maxillary tooth is longer and follows a toothless space, the scales are 

 pitless, and the hemipenis is bifurcate. Rhadincea agrees with Dia- 

 dophis in dentition, but i.as no scale pits, as in Dromicus, and the 

 hemipenis is capitate. Both of these genera are neotropical in distri- 

 bution. The species ot Diadophis are ^JTortli American in distribution, 

 except one from the Bahama Islands. It is, however, not unlikely that 

 other species will be referred to this genus when the characters of 

 their scale pits shall be known. 



The Korth American species of Diadophis are difficult to define, 

 owing to their variability. If exceptions to definitions were to be 

 chiefly considered, all might be regarded as one species. They are 

 easily seen to have been of common origin at no very remote j)eriod. 

 The number of labial scuta is variable in all of the forms; the number 

 of rows of scales is much less so. The width of the yellow neck collar 

 is very variable; in the D. regalis it may be present or absent. The dis- 

 tribution of the spots on the belly, whether regular or irregular, coin- 

 cides with other character quite closely, but the absence of the median 

 series from the form with three rows is of no significance. The light 

 or dark color of the dorsal region characterizes geographical varieties 

 of each of the three North American species. The species are charac 

 terized as follows : 



I. Tail long; urosteges 119; temporals 1-2. . 



Scales in 17 rows; superior labials, 8; ligLt reddisli brown above, white below; 

 unspotted D. ruhescevs. 



II. Tail short; urosteges not more than 60; temporals, 1-1; generally a collar. 



Scales in 17 rows; superior labials, 7; labials, throat, and belly, irregularly 



• spotted I), regalis. 



Scales in 15 rows; superior labials, 7; labials, throat, and belly irregularly 



spotted 7J». amahilis. 



Scales in 15 rows; superior labials, 8; labials, throat, and belly unspotted, or the 

 belly with a median series of spots D. imnctatus. 



The Diadophis rubescens Cope,Mnhabits tiie Bahaman Island of New 

 Providence. The D. punctatus is restricted to the eastern region of 

 Nearctica; the D. amabilis belongs to the Central, the Pacific, and the 

 Sonoran, while the D. regalis is Sonoran, extending its range as far 

 south in Mexico as the Tierra Templada of Vera Cruz. 



"Proc. Amer. Phil. Soc, 1885, p. 403. 



