16 DR. A. GiJNTHER ON A NEW WEST-AFRICAN SNAKE. [Jan. 13, 



3. The height of the body one-fifth or one-sixth of the 



total length ; the height of the dorsal fin two- 

 thirds of the length of the head. L. lat. 170. 

 The gill-cover overlapping the root of the pec- 

 toral. S. cambricus. 



4. The height of the body one-fourth of the total 



length ; the height of the dorsal fin equals the 

 length of the head without snout. L. lat. 165. 

 The gill-cover not overlapping the root of the 

 pectoral. S. willughbii. 



II. Lower jaw very feeble ; teeth minute. 



1 . The pectoral extending to, or beyond, the origin of 



the dorsal fin. S. grayi. 



2. The pectoral terminating at a considerable distance 



from the origin of the dorsal fin. S. colii. 



2. On Atheris burtonii, a New Snake from West Africa. 

 By Dr. Albert Gtjnther. 



(Plate III.) 



A collection made by Major Burton, H. M. Consul in Fernando 

 Po, during an excursion in the Camaroon country, contained several 

 species of Snakes, namely, Grayia triangularis, Bryiophis hirtlandii, 

 a brood of newly-born Clotho nasicornis*, and, finally, a specimen of 

 a Snake distinguished by its form, scales, and shields, and by a colo- 

 ration which is almost unique in the whole order of Ophidians. I 

 had named this genus Poecilostolus (Ann. & Mag. Nat. Hist. Jan. 

 1863) ; but having since received the last part of ' Proc. Acad. Nat. 

 Sc. Philad. 1862, I find that Mr. Cope has already proposed the 

 generic name oi Atheris for congeners of our species (p. 337). 



Atheris. 



Head thick, broad, triangular, covered above with strongly-keeled 

 scales ; body compressed ; tail prehensile. Scales keeled. Sub- 

 caudal shields entire. 



Atheris burtonii. (PI. III.) 



The head and neck are rough, in consequence of the keels of the 

 single scales forming prominent spines. The rostral shield is very 

 low, linear, with other scale-like shields above ; nine upper labials. 

 Nostril in the middle of a single subquadrangular plate, situated 

 above the first labial ; eye surrounded by a ring of subequal scales ; 

 chin-shields scale-like, keeled, except the anterior pair, which are 

 smooth ; the posterior labial shields of the lower jaw keeled. Scales 



* There is also a specimen, in a very bad state of preservation, which appears 

 to belong to Neusterophis lavissima {Natrix lavmhna, Gthr.). 



