422 REPORT OF NATIONAL MUSEUM, 1«08. 



inferior surfaces smootli, except those of the tibia and forearm, which 

 are keeked and mucronate. Colhir serrate except at middle. The hind 

 lej? extended falls short of the axilla. The tail is rather long, exceed- 

 ing by a little twice the length of the head without the horns. First 

 and fifth toes of equal length on both extremities. Femoral pores 

 eleven to fifteen on each side, the rows continuous on the median line, 

 or nearly so. 



Aleasnremcnts (Sonora). — Total length, 140 mm.; length to vent, 89 

 mm.; length to gular fold, 10.5 mm.; length of head Avith horns, 32 mm.; 

 length of head without horns, 22 mm.; Width of head at temporal 

 region, 19 mm.; length of fore leg, 40 mm.; length of fore foot, 12 mm.; 

 length of hind leg, 49 mm.; length of hind foot, 20 mm. 



General (;olor above light brown; median line pale; lateral nuchal 

 spots present, obscure; three or four pairs of blackish blotches on each 

 side of the median line, which are of irregular outline, concave for- 

 ward, and not fused into transverse bands; tail and limbs with broad, 

 brown cross bands; inferior surfaces immaculate; head light brown, 

 horns paler. 



This species occupies an isolated position in the genus for several 

 reasons. The presence of four equally developed occipital horns instead 

 of the two which characterize all the other species, the continuity of 

 the femoral pore series across the middle line, and the tuberculation 

 of the scales are the principal ones. The squamation is like that of 

 the coronation group, but in the short series of scales ending in the 

 temporal horns it is more like the cornutum group, with which it 

 also agrees in the matters of iufralabials and inferior gular scales. 



Specimens of this species display some noteworthy differences. In 

 two Arizona individuals the temporal and occipital horns are in a 

 single slightly curved plane. In the specimen from Sonora, above 

 described, the second and third (posterior) temporals are on a dis- 

 tinctly lower plane. In Cat. No. 161, also from Sonora, these horns are 

 depressed, but less so. In Cat. No. 8437, from Arizona, the series of 

 femoral pores are separated on the middle line by four rows of scales, 

 and the pores number on one side eighteen and on the other twenty. In 

 Cat. No. 17179, from Tucson, the series include twenty pores each, and 

 are separated by one scale on the nnddle line. In my Sonoran indi- 

 vidual but one scale separates the adjacent pores of opposite rows, and 

 the latter contain 11-12 pores. In Cat. No. 101 each row contains seven- 

 teen pores, and five rows separate them at the middle. In Cat. No. 8437 

 there is on each side of the superior side of the tail, beyond the base, a 

 tetrahedral conic scale looking directly upward, which is wanting in the 

 Sonoran specimen. In Cat. No. 8437 one has seven and the other eight 

 large iufralabials; there are seven in the Sonoran individual. Cat. No. 

 17179 has seven on one side and eight on the other. No other differ- 

 ences are observable. 



The Plirynosoma solare is restricted to the Sonoran region. It has 



