728 13. COLUBRIDE 
7% 3 and 14—14 in one, or 4%. The scale-rows are 33 in 
eleven, or 39%; 31 in eleven, or 39%; 35 in three, or 11%; 
29 in two, or 7%; and 37 in one, or 4%; the average is 32.3 
rows. The gastrosteges vary in number from 223 to 263, 
males having from 224 to 252, females from 223 to 263; 
the average in twelve males is 234, in sixteen females, 239. 
The urosteges vary from 50 to 72, males having from 58 to 
72, females from 50 to 67; the average in twelve males is 
64, in fifteen females, 59. 
The dark blotches between head and anus in 28 speci- 
mens vary from 46 to 66, the average being 55. On the 
tail they vary from 12 to 21, and average 15.4. 
Distribution —In California this subspecies occupies the 
Colorado and Mohave deserts and the southern end of the 
San Joaquin Valley. It ranges north and east over most of 
Nevada. 
From Nevada I have examined specimens of this sub- 
species from Humboldt (Thousand Creek Flat, Virgin Val- 
ley, Big Creek Pine Forest Mountains), Washoe (Pyramid 
Lake, Nixon), Ormsby (Carson), Lander (Austin), Elko 
(Carlin), Nye (Peavine Creek, Toiyabe Mountains, Round 
Mountain at 6,300 feet), and Esmeralda (Palmetto Moun- 
tains), counties. 
Californian specimens examined have been collected in 
Imperial (Silsbee), Riverside (Mecca), San Bernardino 
(Victorville, Hesperia), Mono (Benton), Kern (Walker 
Pass, Tehachapi Mountains, Isabella, Delano, Bakersfield, 
Buttonwillow), and San Luis Obispo (Simmler, Poso, Palo 
Prieto, Shandon) counties. 
Remarks.—Some of the specimens from the San Joa- 
quin Valley and eastern San Luis Obispo county approach 
more or less closely to the characters of P. catenifer heer- 
