146 MR. G. A. BOULEXGER ON THE EEPTILES 



fifth, entering the eye; three lower labials in contact with the anterior chin-shields ; 

 posterior chin-shields as long as or a little longer than the anterior, and separated 

 from each other by two series of scales. Scales in 19 rows. Yentrals 160 to 188 ; anal 

 di^ided ; subcaudals 36 to 46. Pale buff or cream-colour above, with a series of large 

 transversely rhomboidal dark spots; a dark median biind along the head and nape, 

 sometimes confluent with an interocular transverse band ; an oblique dark band from 

 the eye to the angle of the mouth ; lower parts uniform white. 



Total length 450 raillim., tail 60. 



This sand-snake was iirst described from a specimen obtained in Algeria in the 

 ^^'estern Desert. Gervais records another from the Souf. A specimen from Batna is 

 in the St. Petersburg Museum. M. Lataste received it from Mraier through jNIajor 

 Oudri, and from Ferriana, in Tunisia, through Dr. Eobert. M. Valery-Mayet found it 

 at Gourbata, near Gafsa, and Marquis Doria has it from Kairnuan. It is also known 

 to occur in the Sennaar, in Arabia, Syria, and Persia. I'igured by Jan, Icon. Gen. 

 Ophid. livr. 10, pi. vi. fig. 2. 



3. Zamenis, Wagler, 1830. 



Maxillary teeth 10 to 20, increasing in size posteriorly; mandibular teeth subequal. 

 Head elongate, distinct from neck ; eye moderate or rather large, with round pupil ; 

 one or more suboculars. Body elongate, cylindiical ; scales smooth or feebly keeled, 

 in 15 to 31 rows, with apical pits; ventrals rounded or with an obtuse lateral keel; 

 tail long ; subcaudals in two rows. 



The study of the species of this genus is a most perplexing one, owing to tlie 

 conqdete passage which exists between many forms which it seems nevertheless 

 necessary to distinguish. As regards the Barbary Z/oneiiis, however, of which only 

 three species are to be distinguished, the only difficulty will be in the definition, otlur- 

 wii^e than by coloration, of Z. alyirus from Z. Iiippocrepis ; I am afraid we must at 

 present content ourselves with the statement that the former has the scales disposed iu 

 25 longitudinal rows and usually one labial entering the eye, whilst the latter has the 

 scales usually in 27 rows (at the point where they are most numerous) and usually the 

 eye completely separated from the labials by a series of suboculars. 



Three other species have been ascribed to the fauna of Barbary, but must be erased : 

 1. Z. florid enUts, Schleg., noticed and head figured by Gervais (Mem. Ac. Montpellier, 

 iii. 1857, p. 512, pi. v. fig. 4), from Laghouat, is, in my opinion, the Z. algirus, and 

 therefore widely different from Schlegel's species. 2. Zamenis atrovirens, Shaw, recorded 

 from Algiers by Giinther (Cat. Colubr. Snakes, 1858, p. 102) from a specimen purchased 

 of a dealer in Paris, and mentioned from Mogador (specimen purchased, 1870) in the 

 list of the animals having lived in the London Zoological Gardens. 3. Zamenis atei; 

 Giinther (Ann. & Mag. N. H. (4) ix. 1872, p. 22), stated to be from Biskra, is a melanotic 

 variety of the South- American Liophis reyinm. 



