the Species of Polypterus. 419 



length ; interorbital space flat or slightly concave ; all the 

 head-shields paired ; mandible projecting very slightly 

 beyond the snout. Dorsal spines 12 or 13, anterior scarcely 

 overlapping when folded, 3 or 4 times as long as broad. 

 Pectoral reaching first dorsal spine or beyond. 54-56 scales 

 along the body, 42-4(5 round the middle. Body with 4 or 5 

 more or less regular dark cross-bars; fins spotted or streaked. 



Total length 50 millim. 



Upper Nile, West Africa? 



A. B. C. D. 



1. Chartoum XII 54 1§ 5f 



2. Nile XIII 56 1§ 4| 



3. W. Africa XIII 56 1§ 5 



4. „ XII 56 1§ 5| 



5 XII 55 lft 5 



5. Polypterus Wteksii, sp. n. 



Head If as long as broad, 4^ times in total length ; inter- 

 orbital region slightly convex ; all the head-shields paired ; 

 snout projecting very slightly beyond the mandible ; sub- 

 operculum very small, smaller than the eye. Dorsal spines 9, 

 anterior 3 to 3^ times as long as broad, not overlapping when 

 folded. Pectoral widely separated from dorsal fin. 57 scales 

 along the body, 44 round the middle, all with granular 

 asperities. Dark olive above, yellow beneath, the two colours 

 sharply delimited on the side; six narrow black bars across 

 the back, with some black spots between them, the last 

 followed by irregular marblings ; a large black spot on the 

 membrane to each dorsal spine ; soft fins with dark and light 

 spots ; pectoral with three blackish cross-bands. 



This species is founded on a single young specimen with 

 external gills, measuring 170 millim., recently obtained at 

 Monsembe, Upper Congo, and presented to the British 

 Museum by the Rev. J. H. Weeks, in whose honour it is 

 named. 



In the reduction of the suboperculum this and the following 

 species lead to Calamichthys, in which the bone has entirely 

 disappeared. 



6. Polypterus senegalus i Cuv. 



Head \'i to 2 as long as broad, 5| to 7 times in total 

 length; interorbital region convex; all the head-shields 

 paired; subopercle smaller than the eye; snout projecting 

 slightly beyond the mandible. Dorsal spines 8-10, anterior 

 separated from each other when folded, 3 to 4 times as long- 

 as broad. Pectoral widely separated from dorsal fin. ~)',}-~j\) 



