LAOERTILA— IGUANIDAE— SCELOPORUS TRISTICHUS. 



571 



" The distinctive characters of these species are as follows: 



11 S. jarrovii. — Parietals, 2; scales in vertebral line from occiput to 

 opposite groin, 39. Dorsal scale, all with yellow centers ; two light hands 

 on side of neck, the upper from the eye and continuous with the anterior 

 border of the collar, the lower commencing at the muzzle ; nape black. 



"8. ornatus. — Parietal single; scales to opposite groin, 50; above black, 

 with two or more longitudinal rows of irregular light spots ; no bands on 

 side of neck ; nape spotted. 



"Dedicated to Dr. H. C. Yarrow, the surgeon and zoologist of the 

 expedition for ' Explorations west of the one-hundredth meridian.' " 



Is scarce in Arizona; but three specimens being secured. 



The plate gives figures of head, vent, and femoral pores and scales of 

 the back. 



No. 



Locality. 



Date. 



Collector. 



PPP 5 

 P P P 5 A 

 1 199 





. iS73 



, 1S73 



Oct., 1S74 



H. W. Henshaw. 

 Do. 

 Do. 



do 



do 





SCELOPORUS TRISTICHUS, Cope, sp. nov. 



Scales of the head smooth; supraorbitals in only three rows ; a median 

 series of transverse plates bounded by a row of small ones internally and 

 externally; frontal divided transversely; interparietal wide as long ; parietals 

 undivided ; scales in forty rows from head to base of tail, well keeled, and 

 strongly mucronate, a little larger than the lateral, which about equal the 

 ventral ; four preauricular free scales ; a granular patch behind lateral fold 

 of the neck ; when the short hind legs are extended forward, the end of 

 the external toe reaches the axilla ; femoral pores sixteen. 



Color above olive-brown, with a pale lateral band on each side, separated 

 by seven rows of scales. This space is crossed by undulating black cross 

 bands, which are interrupted in the middle, and pale-bordered behind ; a 

 brown band from the eye to the middle of the side, where it is broken into 

 spots ; legs and feet black-speckled ; blue of the sides well separated below ; 

 a subround blackish -blue spot on each side the throat. 



