70 PITUOPHIS. 



dilated anteriorly, tapering posteriorly. Prefrontals proportionally 

 small, subcircular. The nasals are nearly equal in size, and the 

 nostrils open between their commissure near the edge of the pre- 

 frontals. Rostral proportionally broad, even with the surface of the 

 snout. Loral small, subelliptical and oblique. Two anteorbitals, 

 the upper one very large, the lower one small, resting on the 

 fourth upper labial. Three postorbitals of nearly the same size. 

 The temporal shields, ten to twelve in number, are slightly larger 

 than the contiguous scales. Upper labials 8, 7th the larger. Lower 

 labials 12, 5th and 6th largest. Posterior mental shields very nar- 

 row, extending beyond the 6th lower labial. Dorsal scales narrow 

 and rather acute, constituting 31 rows, the outer one of which is con- 

 siderably the larger. Tail very tapering. 



Ground-color above fuscous, with a triple series of black blotches 

 along the back, 78 in number, the 61st opposite to the anus ; 17 on 

 the tail. The blotches of the medial series are proportionally very 

 large, quadrangular, longer than broad, covering six rows of scales, 

 and the half of the adjoining rows, embracing longitudinally five or six 

 scales. A narrow light space of one scale exists between each blotch. 

 The adjoining series is composed of much smaller blotches, alternat- 

 ing and covering three rows of scales confluent with the middle ones, 

 thus forming a continuous chain on the back, and enclosing entirely 

 the light spaces between the blotches. A series of subcircular or 

 oblong blotches runs conspicuously along the middle of the flanks, 

 on the 4th, 5th, 6th, and 7th rows of scales. These are 88 in num- 

 ber, the 71st opposite to the anus, and 10 along the anterior half of 

 the tail. The five first blotches are elongated, and exhibit a tend- 

 ency towards forming a vitta or band. From the middle region of 

 the body to the tail, two obsolete series of very small blotches are seen 

 alternating with the series of the flanks, one above and one below. 

 The abdomen is yellowish, unicolor, except a series of blotches on the 

 extremities of the scutellse, extending sometimes to the outer row of 

 scales. 

 San Francisco, Cal. 230. 71. 31. 35. 5|. (on dep.) Expl. Exped. 



