little-known African Silurid Fishes. 529 



of one simple ossified ray or spine and 6 branched rays, the 

 second opposed to the anal and formed of fine soft rays pre- 

 ceded by a short spine ; pectoral and ventral fins moderately 

 large, the former with a spine; 8 rays to the pectoral, 6 to 

 the ventral. No cephalo-nuchal shield. Mouth small, in- 

 ferior, toothless ; lips not much developed; a maxillary and 

 a mandibular barbel on each side; nostrils remote from each 

 other, both with a valve ; eyes small, without free border. 

 Gill-clefts narrowly interrupted at the isthmus. 



Nearest allied to Phractura, from which it is well distin- 

 guished by the position of the anterior dorsal, the presence 

 of a spine in front of each of the dorsals, the presence of a 

 single mandibular barbel, and the total absence of teeth. 



Named in memory of the late Dr. John Anderson, to whose 

 exertions during the latter years of his life Science is indebted 

 for much progress in the zoology of the Nile region, and to 

 whose initiative we owe the organization of a survey of the 

 Nile Fishes which is now being carried on by the Egyptian 

 Government. 



1. Andersonia leptura, sp. n. 



Depth of body 9 times in total length, length of head 

 5 times. Head 1^ as long as broad; skull rugose; snout as 

 long as the postocular part of the head, thrice as long as the 

 diameter of the eye, which is half the interorbital width ; 

 barbels slender, as long as the snout. Occipital process 

 keeled, 2-g- as long as broad, widely separated from the inter- 

 neural shield ; a shorter process on each side of the occipital 

 process. Anterior dorsal I 6 ; first ray longest, nearly as 

 long as the head. Anal I 9. Pectoral § length of head, as 

 long as the ventral, widely separated from the anal. Caudal 

 with crescentic notch. Caudal peduncle depressed, ^ total 

 length. 25 dorsal and 23 ventral scutes, the last 9 on the 

 caudal peduncle. Greyish above, marbled with blackish, 

 white beneath. 



Total length 50 millim. 



A single specimen was found by Mr. Loat in a pond near 

 Koshek, Soudan, in March 1900. 





