SNAKES OF EAST AFRICA. 637 



Family V i p E R i » ,E. 



Synopsis of the Genera. 



1. E.ye moderate or large, separated from the upper laliials hy suboculars ; veiitrals 

 less than 180. 

 Upper surface of liead covered with large symmetrical shields ; 



pupil round Causus. 



Upper surface of head covered with scales ; nasal in contact with 

 'rostral or separated b}' a single (naso-rostral) shield; pupil 



vertical ; subcaudals in two rows Yipera. 



Upper surface of head covered with scales ; nasal sejjarated from the 



rostral by small scales ; pupil vertical ; subcaudals in two rows. JBitis. 

 Upper surface of head covered with scales; im\i\\ vertical; sub- 

 caudals single ; tail prehensile Af/ieris. 



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

 with large symmetrical shields ; no loreal ; a small praaocular 

 usually present; ventrals 178-356 Airactaspis. 



1. Causus. 

 Wagl. Syst. Aniph. p. 172 ; Bouleiig. Oat. Sn. iii. p. 465. 



Synopsis of the Species. 



I. Scales in 17 rows or more ; snbcaxidals all or greater part in two rows. 



Snout obtuse, moderately prominent; ventrals 120-155 C rliomheatus. 



Snout prominent, often more or less distinctly turned up at the 



end; scales in 19 to 22 rows ; ventrals 134-152 C. resimtts. 



Snout prominent, more or less turned up at the end ; scales in 



17 rows ; ventrals 110-125 C defilippii. 



II. Scales in 15 rows; subcaudals single C. Uclitenstfiiiii. 



1 . Causus rhombeatus. 



Sepedon rhombeatus Licbt. Verz. Donhl. Mas. Berl. p. 106. 

 Causv,s rhomheaius Bouleng. t. c. p. 467. 

 Tropical and tSoutli Africa. 



2. Causus resimus. 



Heterophis resimus Peters, Mon. Berl. Ac. 1862, p. 277, pi. — , 

 fig. 4. 



Causus resimus Bovileng. t. c. p. 468. 



East and Central Africa, Angola. 



.3. Causus defilippii. 



TTeterodon defilippii Jan, Arch. Zool. Anat. Pliys. ii. 1862, 

 p. 225. 



Oausus defilippii Bouleng. t. c. p. 469. 



East and Central Africa, S. Rhodesia, Transvaal. 



4. Causus lichtensteinii, 



Aspidelaps lichtensteinii Jan, Rev. et Mag. Zool. 1859, p. 511. 

 Causibs lichtensteinii Bouleng. t. c. p. 470. 



Tropical Africa, from the Gold Coast and Uganda to the Congo. 

 Proc. Zool. Soc— 1915, No. XLIY. 44 



