CICHLID FISHES OF LAKE NYASSA. ' 7l9 



52. Haplochromls mackostoma, sp. n. (PI. IV. fig. 2.) 



Depth of body 3 in length, lengtli of head 2|. Snout with 

 profile a little concave in front of eye, thence straight, declivous, 

 2| as long as diameter of eye, which is 51 in length of head, less 

 than prfeorbital depth, | depth of cheek ; interorbital \\idth 4| 

 in length of head. Jaws equal anteriorly; maxillary consider- 

 ably exposed distally, extending to below anterior ^ of eye ; 

 teeth small, conical, in 6 series. 6 series of scales on cheek. 

 12 gill-rakers on lower part of anterior arch= Pharyngeal teeth 

 slender. 35 scales in a longitudinal series, 6 from origin of 

 dorsal to lateral line. Dorsal XVI 10; last spine i-, longest soft 

 rays less than -k length of head. Anal III 10 ; third spine 

 stronger than dorsals, ^ head. Pectoral | head, not quite 

 reaclnng anal. Caudal very slightly emarginate Caudal 

 peduncle l^ as long as deep. A series of about 8 dark spots on 

 each side of back ; a second series below lateral line, posteriorly 

 confluent to form a band. 



A single specimen, 260 mm. in total length (Wood). 



11. Lethmnops, gen. n. 

 (type Chromis lethrmus Giinth.). 



Differs from Hcq^lochromis in the dentition. Teetli very small 

 a.nd slender, in a fe"\v series, forming narrow^ bands vv'hich ai'e 

 inteiTupted at the symphyses ; outer teeth mostly bicuspid, often 

 iinicuspid posteriorly, inner uni- or tri-cuspid. 



ISTyassa : four species. 



Synopsis of the S'j^ecies. 



I. Pharyngeal teeth all small. 



Snout shorter than postorbital part of head ; maxillary not far 



short of vertical from anterior edge of eye 1. alius. 



Snout longer than postorbital part of head ; niaxillarj- ending 



not far behind nostril 2. macrorhj/nclius. 



II. Last few teeth of two middle series of lower pharj'ngeal somewhat enlarged. 



10 gill-rakers on lower part of anterior arch 3. lethrinus. 



12-i3 gill-rakers on lower part of anterior arch 4. leptodon. 



1. Lethrinops albus, sp. n. 



Tilapia macro j^hthalma (part.) Bouleng. Cat. Afr. Pish. iii. 

 p. 261. 



Depth of body equal to length of head, 3 in length of fish. 

 Snoiit with straight profile, as long as diameter of eye, Avhich is 

 3| in length of head, interorbital width 5, depth of prasorbital 

 4-^. Jaws equal ; maxillary not far short of vertical from 

 anterior edge of eye ; teeth in 2 series. 3 series of scales on 

 cheek. 10 gill-rakers on lower part of anterior arch. Pharyn- 

 geal teeth small. 32 scales in a longitudinal se]'ies, 5 from 



