ART. 12 REVISION" OF LIZARDS OF GENUS CTENOSAURA BAILEY 9 



C^. — First six whorls of spinous scales of the tail separated from each 

 other by fewer than four rows of small, flat scales. 

 D'.— The first and second or the first, second, and third whorls of 

 spinous scales separated from each other by two or three 

 rows of small, flat scales, the next six or eight whorls being 

 separated from each other by two rows of small, flat scales, 

 body marked with black cross bands terminating oii belly 



similis 

 D*. — First five or six whorls of spinous scales separated from each 

 other by three rows of smaller scales, the next five or six 

 whorls being separated from each other by two rows of 

 smaller, flat scales. No such black bands as in D...pectinata 

 A2. — Median row of dorsal scales low and interrupted at the sacrum, not contin- 

 uous ss in A'. 

 B'. — Median row of dorsal scales extending only one-fourth to one-half dis- 

 tance to sacrum, and not noticeably raised. 

 C. — Tail armed with 13 to 20 whorls of heavy spinous scales not int< 



spaced with whorls of small flat scales defensor 



C^. — Tail armed with whorls of spinous scales, which are interspaced 

 with one row of small flat scales. 

 D'. — Row of small flat scales very conspicuous throughout length 



of tail clarki 



D2. — Row of small flat scales barely detectable on basal half cf 



tail, but noticeable on distal half erythromelas 



B^. — Median row of dorsal scales extending to or almost to sacrum, notice- 

 ; bly raised, of medium height. 

 C. — First two or more whorls of caudal spinous scales separated from 

 each other by one row of small flat scales. 

 D'. — Males and females possessing very pronounced dewlap 



palearis 

 D^. — Not possessing dewlap but having transverse gular fold 



quinquecarinata 

 C^. — Proximal whorls of caudal spinous scales separated by two or 

 more rows of small flat scales. 

 D'. — First, second and third worlhs of caudal spinous scales inter- 

 spaced with two rows of small flat scales, the next five or 

 six whorls with one row of small flat scales. 



E^ — Small dewlap present bakeri 



E^. — No dewlap, transverse gular fold present, back marked 



with prominent black blotches or spots hemilopha 



D2. — First three or more whorls of caudal spinous scales interspaced 

 with three or more rows of small flat scales. 

 E*. — First and second or first, second and third whorls of spin- 

 ous scales interspaced with three rows of small flat 



scales acanthura 



E^. — First, second, third, fourth, and fifth whorls of spinous 

 scales interspaced with three rows of small flat scales 



braohylopha 

 DISCUSSION OF THE SPECIES 



CTENOSAURA ACANTHURA (Shaw) 



Plates 1, 2, 3, 4 



Lacerta acanthura Shaw, 1802, General Zoology, vol. 3, p. 1, p. 216. — Gray, 1827, 



Philos. Mag., ser. 2, vol. 2, p. 57. 

 Uromastyx acanthurus Merrem, 1820, Tent. Syst. Amph., p. 56. 



