SYNOPSES ANi) DESCRIPTIONS. ^3 



with a narrow black line. Dorsal scales in 15 rows. Ventrals 193. Anal 

 entire. Subcauclals 57 pairs. (From closer.) Rio San Pedro of Rio 

 Grande. 



DiADOPHIS REGALIS. 



Baifd ct- Giranl, 1853, Cat. N. A. Serp., 115. 



" Body above uniform greenish-ash ; beneath light yellow, scattered all 

 over with small black spots. No occipital ring. Dorsal scales in 17 

 rows. Ventrals 237+1+58 pairs." Sonora, Mexico. 



A specimen of this species from San Luis Potosi has 210 ventrals. 

 Anal bifid, and 73 pairs of subcaudals. The lower surface of the tail and 

 hinder abdomen ai-e a bright orange I'ed, shading to yellow forward. Belly 

 sjiotted irregularly with black. Labials and chin-shields with black spots 

 on their hinder margins. Scales in the outer row dark with yellow bases, 

 medials dark, finely sprinkled with ashy. 



The three preceding species of I)iado])Jus are very closely related. I 

 am inclined to consider them as one, which, through several varieties, 

 gradually increases in length, number of ventral plates and brilliancy of 

 coloration from New Eno'land to Mexico. 



'c 



Rhinocheilus. 



Baird & Girard, 1853. 



Body elongate, tapering little to head and tail, slightly compressed ; head 

 small, rather indistinct, narrow, crown convex, snout produced, pointed; 

 tail short, tapering regularly. Maxillary teeth equal, smooth, without 

 interspaces between anterior and posterior. Crown-shields nine. Rostral 

 prominent, bent back on the top of the snout. Nasal in two parts, nostril 

 between. Loreal present. Oculars 1 — 2. Scales smooth, short, broad, 

 in 23 rows. Anal entire. Subcaudals entire or divided (the specimen 

 before me has nineteen of the posterior divided). 



Rhinocheilus lecontei. 



Baird & Girard, 1853, Cat. N. A. Serp., 120. 



Long, slender, subcylindrical, belly flat ; head rather indistinct from the 

 neck, little larger, crown convex, narroAv and pointed in front; tail short, 

 near one eighth of the total, stout, tapering. Posterior upper maxil- 

 lary teeth stouter. Mouth-cleft medium, slightly curved. Eye moderate, 

 pupil subcircular (apparently a little oblong, erect). Rostral prominent, 



