16+ 3. IGUANID.^ 



27. Callisaurus ventralis myurus Richardson 



Northern Gridiron-tailed Lizard 



Plate 13 



? Holbrookia Cope, Proc. Acad. Nat. Sci. Phila., 1883, p. 18. 



? ? Callisaurus species Merriam, N. Amcr. Fauna, No. 7, 1893, p. 172. 



Callisaurus ventralis myurus Richardson, Proc. U. S. Nat. Mus., Vol. 48, 

 1915, p. 408 (type locality. Pyramid Lake Indian Agency, 

 Washoe County, Nevada) ; Camp, Univ. Cal. Pubis. Zool., 

 Vol. 17, No. 7, 1916, p. 70; Stejneger & Barbour, Check List 

 N. Amer. Amph. Kept., 1917, p. 47; Van Denburgh & Slevin, 

 Proc. Cal. Acad. Sci., Ser. 4, Vol. XI, 1921, pp. 28, 32. 



Description. — Head rather short and low, with well 

 developed canthus rostralis. Nostrils large, opening on 

 upper surface of snout. Supraocular regions covered with 

 small plates and separated from each other by one or two 

 rows of slightly larger plates. Upper head plates (except 

 interparietal) small and irregular, largest on frontal and 

 prefrontal regions, everywhere smooth and rather flat. 

 Several subocular plates, middle one very long and strongly 

 keeled. Superciliaries rather small, but strongly imbricate. 

 Eyelids bearing a well developed fringe. Supralabials 

 strongly imbricate, and produced laterally so as to form a 

 series of curves when seen from above. Infralabials small, 

 juxtaposed. Below them, one or more series of flat sub- 

 labial plates. Gulars granular and smooth, growing larger 

 and imbricate on posterior fold. Back and sides covered 

 with small flattened granules, which change gradually into 

 much larger smooth ventrals. A dermal fold usually extend- 

 ing along each side between limbs. Tail of moderate length, 

 much flattened; its scales slightly imbricate, and along its 

 edge, pointed. Limbs very long and slender. Ear-open- 

 ing large, without denticulation. Femoral pores varying 

 from 11 to 17, average in 100 thighs, 13.77, 



The general color above is grayish, dotted and spotted 



