AFRICAN SNAKES. 221 



3. Causus DEFILIPPII. 



Heterodon defilippii Jan, Arch. Zool. Anat. Phvs. ii. 1862 r 

 p. 225. 



Causus 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. 

 Causus lichtensteinii Bouleng. t. c. p. 470. 

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



2. Bitis. 

 Gray, Zool. Miscell. p. 69 ; Bouleng. Cat. Sn. iii. p. 492. 



Synopsis of the Species. 

 I. One or two series of scales between the nasal and the rostral. 



Nostrils directed entirely upwards ; scales in 29 to 41 rows B. arietans. 



Nostrils directed upwards and outwards ; scales in 25 or 27 rows . B. peringueyi. 

 Nostrils directed upwards and outwards ; scales in 22 to 29 rows ; 



an erect horn-like scale above the eye (rarely absent) B. caudalis. 



II. Four or five series of scales between the nasal and the rostral ; 

 scales in 33 to 41 rows. 

 A single enlarged, sometimes horn-like scale above the internasal, 



in contact with its fellow B. gabonica. 



Two or three enlarged, horn-like scales above the internasal, 



usually with small scales between them and their fellows B. nasicornis. 



1. BlTIS ARIETANS. 



Vipera arietans Merr. Tent. p. 152 ; Bocage, Herp. Ang. 

 p. 149. 



Bitis arietans Bouleng. t. c. p. 493. 



Tropical and South Africa ; Southern Arabia. 



2. Bitis peringueyi. 



Vipera peringueyi Bouleng. Ann. & Mag. N. H. (6) ii. 1888 r 

 p. 141. 



Vipera heraldica Bocage, Herp. Ang. p. 151, pi. xvi. fig. 1. 

 Bitis peringueyi Bouleng. t. c. p. 495. 

 Angola, Damaraland, Kalahari. 



3. Bitis caudalis. 



Vipera caudalis A. Smith, 111. Zool. S. Afr., Rept. pi. vii. ; 

 Bocage, Herp. Ang. p. 450. 



Bitis caudalis Bouleng. z. c. p. 498. 

 Angola and South Africa. 



4. Bitis gabonica. 



Echidna gabonica Dum. & Bibr. Erp. Gen. vii p. 1428 y 

 pi. lxxx. b. 



Proc. Zool. Soc— 1915, No. XVI. 16 



