(556 MR. C4. A. BOULENGER ON THE 



2. ISTaia nigricollis Reinh. Yid. Selsk. Ski'ift. x. 1843, p. 269, 

 pi, iii. figs. 5-7; Bouleng. t. c. p. 378. 



Senegambia and Upper Egypt to Becliuanaland and Natal. 



3. Walterinnesia. 

 Lataste, Le Natur. 1887, p. 411 ; Bouleng. Cat. Sn. iii. p. 392. 



1. WalteriNjSTESIa ^gyptia Lataste, 1. c. ; Bouleng. 1. c. 

 -Nubia? Egypt? 



4. Dendraspis. 



Schleg. Versl. Zool. Gen. Amsterd. 1848; Bouleng. Cat. Sn. iii. 

 p. 434. 



Two species : — 



Second upper labial much deeper than first B. angusticeps. 



Second upper labial not deeper than first I>. antinorii. 



1. Dendraspis angusttceps. 



Naia angusticeps A. Smith, 111. Zool. S. Afr., Rept. pi. Ixx. 

 Dendraspis angusticeps Bouleng. t. c. p. 437. 

 East and Central Africa, Angola, South Africa. 



2. Dendraspis antinorii Peters, Mon. Berl. Ac. 1873, p. 411, 

 pi. i. fig. 2; Bouleng. 1. c. 



Abyssinia. 



Family V i p e r i d .ai:. 



Synopsis of the Genera. 



I. Eye moderate or largei' separated from the upper labials by suboculars. 



A. Upper surface of head covered with large symmetrical 



shields; loreal present ; pupil round ; ventrals 120-155 . Causufi. 



B. Upper surface of head covered with scales ; pupil vertical ; scales strongly 



keeled ; ventrals 130-205. 

 Lateral scales not smaller than dorsals, without serrated keels ; sub- 



caudals in two rows Bitis. 



Lateral scales smaller than dorsals, oblique, with serrated keels ; 



subcaudals in two rows Cerastes. 



Lateral scales smaller than dorsals, oblique, with serrated keels ; 



subcaudals single JEchis. 



II. Eye minute, with round pupil ; upper surface of head covered 



with large symmetrical shields ; no loreal ; ventrals 212-245. Airaetaspis. 



1. Causus. 

 AVagl. Syst. Amph. p. 172 ; Bouleng. Cat. Sn. iii. p. 465. 



Two species : — 



Snout obtuse, moderately prominent; dorsal scales more or less 



' , distinctly keeled . :..'. , C. rhomheatvs. 



Snout prominent, more or less distinctly turned up at the- end; 



scales smooth or ftiiiitlv keeled '.■...•.•...'..■.'..'...;.•.•...•.. ■ C resiiilii.t^ . 



