OF PISHES FKOM LAKE TANGANYIKA. 



21 



22. Perissodus microlepis, sp. n. (Plate VI. fig. 2.) 



10 teeth on each side of the prsemaxillary, 9 on each side of the mandible. Depth 

 of body 3§ times in total length, length of head 3|. Snout a little longer than 

 diameter of eye, which is 4 times in length of head, and almost equals interorbital 

 width; lower jaw projecting; maxillary extending to below anterior border of eye; 

 3 series of scales on the cheek ; large scales on the opercle. Gill-rakers rather long, 

 14 on lower part of anterior arch. Dorsal XVIII 10 ; spines increasing in length to 

 the last, which measures f length of head ; longest soft rays § length of bead. 

 Pectoral § length of head. Ventral not reaching vent. Anal III 8 ; third spine 

 longest, nearly as long as longest dorsal ; longest soft rays half length of head. Caudal 

 truncate. Caudal peduncle 1| as long as deep. Scales 65 ^ ; lat. 1. g^. Uniform 

 dark reddish brown ; a blackish opercular spot. 



Total length 100 millim. 



A single specimen from Mbity Eocks '. 



1 I think it desirable to allude here briefly to two remarkable genera of Cichlidce from Lake Tanganyika, 

 which I have founded on specimens obtained by Capt. Descamps and sent to me for study by the 

 Administration of the Congo Free State. The specimens are in so bad a condition that it will never be 

 possible to draw up from them complete definitions of the species, but their dentitions, which indicate 

 remarkable new genera, are well preserved, and I am sure the annexed figures together with the short notes 

 here given will be sufficient to ensure their future recognition : — 



Ectodtjs, g. n. — Teeth very small, conical, in two series in both jaws, the outer larger ; outer mandibular 

 teeth pointing outward, perpendicular to the others ; maxillary concealed under the prasorbital when the 

 mouth is closed. Scales rather large, ctenoid. Dorsal with 14 spines, anal with 3. 



Ectodus descampsi, sp. n. (Fig. 1, a.)— D. XIV 14 ; A. Ill 8. Depth of body 3f- times in total length, 

 length of head 3. Eye very large, 24 in length of head, If interorbital width. Two series of scales on the 

 cheek. Sc. 34 £ ; lat. 1. f|. Total length 95 millim. 



Ectodus melanogenys, sp. n. (Fig. 1, h.)— D. XIV 16 ; A. Ill 13. Depth of body 5 times in total length, 



Fig. 1. 



V. 



h. 



length of head 3-3-. Eye 4 times in length of head, 1| in length of snout, 1\ interorbital width. Three series 

 of scales on the cheek. About 35 scales in a longitudinal series. A black spot on the chin. Total length 

 95 millim. 



