CROCODILIANS, LIZARDS, AND SNAKES. 821 



PHYLLORHYNCHUS Stejneger. 

 Pliyllorhynchus Stejneger, Proc. U. S. Nat. Mus., XIII, 1890, p. 1")!. 



Head slightly distinct, short; tail short; palatine teeth present; 

 dentition diacranterian ; rostral plate greatly enlarged, with free lateral 

 borders, and produced backward so as to separate the supranasals 

 entirely; anal undivided; no scale pits; pupil vertical; two nasals; 

 loreal present; supralabials not in contact with orbit; one pair of 

 geneials only. 



This genus is a curious example of those snakes in which the rostral 

 shows a most extraordinary develoiDment. In the present instance this 

 shield resembles a thick leaf loosely attached to the front of the snout 

 and turned over on top of the muzzle. It approaches very closely the 

 Lytorhynclms Peters of the desert regions of Korth Africa and India, 

 differing only in the greater posterior jirolongation of the rostral shield. 

 Two species are known, both from the Sonoran region. They differ as 

 follows : 



Scales keeled ou posterior two-tbirtls of body ; tail one-eighth of total length ; about 

 fifteen dorsal and no lateral spots Ph. hroxnii Stejneger. 



Scales all smooth; tail shorter, about one twelfth the length; about thirty dorsal 

 spots and one or two rows of lateral spots Pli. decurtatus Cope. 



PHYLLORHYNCHUS BROWNI Stejneger. 



PhyUoryiicJiKS broicni Stejneger, Proc. U. S. Nat. Mus., XIII, 1890, p. 152. 

 Lytorhytichus hrouni Boulengek, Cat. Snakes Brit. Mus., I, 1893, p. 417. 



Scales distinctly keeled ou the posterior two-thirds of the body, in 

 nineteen rows; four loreals; labials, six and nine; gasterosteges, one 



Fig. 184. 



PHYLLORHYNCHUS BROWXI STEJNEGER. 



X 1.5. 

 Tucson, Arizona. 



Cat. No. 1571H, U.S.N.M. 



hundred and fifty-nine; anal entire; urosteges, thirty-one, divided; tail 

 about one-eighth of total length; upper surface with about fifteen 

 saddle-shaped brownish blotches on back and tail; no lateral spots. 

 Rostral very prominent and broad, recurved on the top of the snout so 

 as to separate the supranasals entirely and the prefrontals partially, 

 with free lateral edges which are rather sharp and thin; lower side of 

 rostral deeply concave; two prefrontals; frontal large, hexagonal, as 

 broad as long; parietals scarcely longer than frontal, their width equal- 

 ing their length ; at their posterior border a broad but very short shield 



