372 DR. H. GADOW ON EVOLUTION [Mar. 20, 



The adults have the upper parts clove-brown, with three rows 

 of more or less obsolete black spots on the back, and vertical bars 

 on the sides. There are no light stripes. The throat is spotted 

 with black ; the chest and belly are straw-coloured, tinged with 

 green, and varied with black and red, the pale scales being black- 

 edged. The under surface of the thighs, hands and feet, and of 

 the distal half of the tail is bright vermilion. 



This race presents an unmistakable desert type, verging as it 

 does towards the monochrome condition, with few dark spots. 



The isolated occurrence of these lizai'ds, and their bright- 

 coloured vmder parts, combined with the comparatively large 

 number of pores, femoral and humeral scales, justify their sub- 

 specific i-ank to C. tessellatus, with which they are closely allied. 



Onemidophorus melanostethus Co])e= vcti'iolosus Cope. 



The types of melanostethus in the Smithsonian Mus. are from 

 the Lower Colorado River, others from Tucson and Fort Lowell 

 in Arizona. The single type of 0. variolosus is from Pai-ras in 

 Coahuila. Dr. Meek brought identical specimens from Lerdo in 

 Nuevo Leon. These four localities lie in an almost straight line. 



This small species measures, adult, from 62 to 86 mm. Its 

 most striking character is the coloration : black-blue under parts ; 

 upper parts bluish, all over vermiculated and spotted with white. 



The following description refers to a male and a female specimen 

 from Lerdo : — 4 supraoculars, with granules behind. No fren- 

 ocular. Collar composed entirely of very small scales, and 

 granules in several rows from the edge of the collar. Humerus 

 of the male with 3 large and 3 smaller rows ; of female with 

 .5 large and 1 smaller row. 



Front of forearm : male with 3 complete very regular rows ; 

 female with 3 very irregular rows. Posterior side of arm entirely 

 granular. Femur with 6 to 7 rows. Tibia with 2 large and 1 

 or 2 smaller rows. Preanal isthmus with 2-3 rows of small 

 scales. 



Pores : male 22/23 ; female 23/25. Two specimens from Fort 

 Lowell have 18/19 and 21 pores. Cope's type-specimen from 

 Coahuila is said to have 25 pores (pp. 568, 587), but the figure on 

 p. 588 shows only 20. The hind limb of the type is said to reach 

 the prenasal plate. That of the Lerdo male reaches between ear 

 and eye ; that of the female reaches the posterior angle of the 

 eye. 



Coloration of male : Throat blue, collar and chest black ; 

 abdomen black with white edges to the scales ; tail below much 

 speckled with black-blue. Female : Throat, collar, and chest blue ; 

 abdomen blue with white-edged scales ; thighs blue and white ; 

 tail mostly blue. — Upper surface : bluish ground-colour, all, 

 vermiculated and spotted with yellowish white ; in the female 

 without traces of stripes, while in the male stripes 2 and 3 are 

 still discernible. In a female specimen from Fort Lowell, British 

 Mviseum, 70 mm., with eggs, stripe 1 is nearly gone, while stripes 



