80 NOTOPTEBID-E. 



These fishes, which constitute an isolated group having affinities with the 

 Mormyridae, live in marshes and lakes, fresh-water or brackish, and feed on worms 

 and insects. Nothing is known of their breeding-habits and development. 



Two genera only: Notopterus, Lacep., with three species from India, Burma, and 

 the Malay region, and one from West Africa, and Xenomystus, Gthr., here described. 



1. XENOMYSTUS. 



Giinther, Cat. Fish. vii. p. 479 (1868) ; Bcmlenger, Poiss. Bass. Congo, p. 118 (1901). 



Body elongate and very strongly compressed, tapering behind, the vent far forwards ; 

 scales very small and cycloid ; lateral line more or less distinct ; a double series of 

 erectile spines forming a ventral serrature. Mouth large, with small and numerous 

 sharp teeth forming a narrow band, with an outer series of larger teeth ; maxillary 

 overlapped by the suborbitals ; teeth on the vomer, the palatines, the pterygoids, the 

 parasphenoid, and the tongue. Nostril widely separated, the posterior near the eye, 

 the anterior with a tentacle. No pseudobranchiae. Three branchiostegal rays. No 

 dorsal fin ; anal fm much elongate, beginning immediately behind the vent and confluent 

 with the small rudimentary caudal. Ventral fins rudimentary. Air-bladder forked 

 behind, prolonged on each side of the caudal region. Vertebrae 70 (10 + 60). 



A single species, inhabiting a considerable part of Tropical Africa. 



1. XENOMYSTUS NIGPI. 

 (Plate XIV. fig. 1.) 



Notopterus nigri, Giinther, Cat. Fish. vii. p. 481 (1868). 



Notopterus (Xenomystus) nili, Stein daehner, Sitzb. Ak. Wien, lxxxiii. i. 1881, p. 196, pi. iv. fig. 2. 



Notopterus {Xenomystus) nigri, Steindachner, Notes Leyd. Mus. xvi. 1894, p. 85. 



Xenomystus nigri, Boulenger, Poiss. Bass. Congo, p. 118 (1901). 



Depth of body four and one-third to five times in the total length, length of head 

 six to seven and three-fourths times. Snout very short, shorter than the eye, the 

 diameter of which is contained three to three and a half times in the length of the 

 head and equals or nearly equals the interocular width ; mouth very oblique, extending 

 to below the anterior third or the centre of the eye ; nasal tentacle long and attenuate, 

 measuring three-fifths to two-thirds the diameter of the eye ; praeorbital, suborbitals, 

 praeoperculum, and mandible with the edge strongly serrated ; preeoperculum with a 



