Acanfhodadtjlus. 53 



The six forms here defiued are not always easy to distinguish, 

 owing to iutergradation. The following synopsis will help in their 

 identification. 



I. Scales in middle of body smooth or feebly keeled : if strongly keeled, convex ; 



tail of yoimjj red. 



Subocular not reaching the oral border, or entering it very 

 narrowly ; suture between the nasals i to ,V the length of 

 the frontonasal Forma typica. 



Svibocular largely bordering the mouth ; suture between the 

 nasals rarely more than i the length of the fr^mtonasal 



Var. belli, Gray. 



Subocular separated from the oral border by a small shield 

 detached from it ; suture between the internas.-ils ^ the 

 lengtli of the frontonasal Var. atlanticus, Blgr. 



II. Scales in middle of body flat, with strong, well-defined keels. 



Sulioeular bordering the moutli ; tail red in the young 



Var. mauritanicus, Douni. 



Subocular usually not reaching the mouth ; prefrontals in 



contact with each other; tail blue in the young . Var. blanci, Doum. 



Subocular usually not reaching the mouth ; prefrontals often 

 separated by one or two shields ; frontonasal often divided 

 into two ; tail red in the young . . . Vai: lineomaculatus, J) &B. 



2. ACANTHODACTYLUS TRISTEAMI. 



.'' Scajjfeira leiocerca. Gray, Ann. N. H. i, 1838, p. 281. 



Zoofoca tristrami, Griinth. Proc. Zool. Soc. 18(34, p. 491 ; Tristram, 

 Faun. Palest, pi. xvi, fig. 2 (1884). 



Acanthodacfylvs dorsalis, Peters, Mou. Berl. Ac. 1869, p. 62. 



Acanthodacfi/Jus tristrami, Bouleug. Proc. Zool. Soc. 1881, p. 746, 

 pi. Ixiv, fig. 1 ; Lataste, Ann. Mus. Geneva (2) ii, 1885, p. 482 ; 

 Bouleug. Cat. Liz. iii, p. 68 (1887), and Bull. Soc. Zool. France, 1918, 

 p. 147. 



Lacerta platijura, Hempr. it Ehrenb. Symlj. Phvs., Zool., Amph. 

 pi. ii, fig. 8 (1899). 



Habit rol)ust, body depressed. Head about l^ to IJ times as long 

 as broad, its length 4 to 4f times in length to vent, its depth equal to 

 the distance lietween the anterior corner or the centre of the eye and 

 the tympanum ; a rather feeble concavity between the prefrontals and 

 along the anterior half of the frontal ; snout obtusely pointed, with 

 obtuse cauthus and feebly concave loreal region ; nasals not or but 

 very feebly swollen, Pileus If to 2 times as long as broad. Neck as 

 broad as the head or a little broader. The hind limb reaches the axil 

 or the shoulder in males as in females ; foot 1,\ to Ii times as long as 



