SNAKES OF NORTH AFRICA. 301 



Tropidonotus natrix Boaleng. t. c. p. 219, 



Algeria and Tunisia north of the Atlas, Eiu'ope, Western 

 Asia. 



2. Tropidonotus tessellatus. 

 CoroneUa tessellata Laur. Sj'n. Rept. p. 87. 

 IVopidonotus tessellatus Bouleng. t. c. p. 233. 

 N.E. Egypt, Europe, Western Asia. 



3. Tropidonotus viperinus. 



Coluber vi2)erinus Latr. Hist. Rept. iv. p. 49. 

 Tropidonotus viperinus Bouleng. t. c. p. 235. 



Morocco, Algeria, Tunisia, Spanish Peninsula, France, Switzer- 

 land, Italy. 



2. Zamenis. 



Wagl. Syst. Amph. p. 188 ; Bouleng. Cat. Sn. i. p. 379. 



Si/nopsis of the SjJecies. 



I. A pair of inteniasals and a pair of pnefrontals. 



A. Scales in 19 rows ; two labials entering the eye. 

 Frontal anteriorly not or but little broader than the supraocular ; 



ventrals 205-218; subcaudals 98-132 Z. daldii. 



Frontal anteriorly considerably broader than the supraocular ; 



ventrals 212-262 ; subcaudals 113-154 Z. rhodorhachis^ 



Frontal anteriorly considerably broader than the supraocular; 



ventrals 195-201; subcaudals 95-105 Z.rogersi. 



B. Scales in 21 (rarely 23) rows, smooth ; two labials enter- 



ing the ej-e; ventrals 198-228; subcaudals 79-111 Z.flonilentus. 



C. Scales in 23 or 25 rows, obtusely or faintly keeled ; usually 



a single labial entering the eye ; ventrals 197-216 ; sub- 

 caudals 70-101 Z. nummifer. 



D. Scales in 25 to 29 (rarely 23) rows, smooth. 



Scales usually in 25 rows ; usually one labial entering the eye ; 



ventrals 214-232 ; subcaudals 87-104 Z. algirus. 



Scales in 25 to 29 rows ; eye usually separated- from the labials 

 by a series of suboculars ; ventrals 222-258 ; subcaudals 

 77-107 Z. hippocvepis^ 



ir. Prefrontals broken up into 3 or more shields ; eye separated 

 from the labials by suboculars ; scales in 25 to 31 rows, 

 usually more or less obtusely keeled ; ventrals 210-278 ; 

 subcaudals 65-110 Z. diadema. 



1. Zamenis dahlii. 



Tyria dcMii Eitzing. N. Class. Rept. p. 60. 

 Zamenis dahlii Bouleng. t. c. p. 397. 

 N". Egypt, S.W. Asia, S.E. Europe. 



2. Zamenis rhodorhachis Jan, in De Filippi, Viagg. Pers. 

 p. 356 ;• Bouleng. t. c. p. 398. 



Egypt to Somaliland, S.W. Asia. 



