1 r)8 MR. C. TATE BEGAN ON THE 



in the livke from two ancestral types, Limiiotilwpia and llaplo- 

 chromis; but, although there are a number of genera Avhich 

 appear to be derived from Haplochromis, that genus itself is 

 represented by two species only. 



From Nyassa 84 Cichlida? belonging to 14 genera* have been 

 described, nearly all endemic. The most striking feature is the 

 pi'esence of 53 endemic species of Ilaplochromis, which appear to 

 form a natural group and have evidently evolved in the lake 

 from one or a few ancestral forms. Of the endemic genera four 

 (with 12 species) are evidently derived from forms closely related 

 to species of Haplochromis now living in the lake, and two more 

 [CynoUlapia, Pseudotropheus) are related to Haplochromis. Of 

 the others Hemitilapia and Otop)harynx are near Tilapla., CMlo- 

 tilapia is Otopharyvx specialized, and Coremalodus is mainly 

 distinguished from the endemic Tilcqna sqioamijnnnis hj its 

 mouth and dentition. The indications are that the endemic 

 Nj'assa Cichlids have originated in the lake from about half-a- 

 dozen ancestral forms. 



In Lake Victoria there are 50 species of Cichlidse, all peculiar 

 to the lake except Tilapia zillii, a Nilotic species. The endemic 

 species are a Tilajna, 44 Hcqjlochromis, and 4 monotypic genera 

 distinguished from Haplocliromis by peculiarities of the dentition, 

 or in one by an increased number of anal spines. 



The species of Haplochromis exhibit almost as great a diversity 

 as in Nyassa, yet there are certain features which enable one to 

 say almost at a glance to which lake a species belongs. In most 

 of the Nyassa Haplochromis the caudal fin is more or less 

 distinctly emarginate, and is covered Avith small scales in the 

 adult fish, whereas in most of the Victoria species it is rounded 

 or truncate and is scaly only in the basal half. In the Nyassa 

 Haplochromis a few distinctive types of coloration are prevalent — 

 for example, 15 species have a dark band on each side from nape 

 to caudal fin, and several others have four dark spots on each 

 side ; in most of the Victoria Haplochromis, when markings are 

 present, they take the form of regular dark ci'oss-bars with a 

 dark band from head to caudal fin and another above the lateral 

 line. 



There can be little doubt that Haplochromis cinereus, a small 

 species, with rather short decurved snout and moderately small 

 and slightly oblique mouth, is a generalized type ; species with 

 these characters are widely distributed in African rivers. A 

 number of species in Lake Victoria are closely related to 

 H. cinereus, but differ in the dentition of the jaws or of the 

 pharyngeals, in having thicker lips, more gill-rakers, a larger 

 eye, etc. 



Haplochromis serramis and its allies are somewhat larger 



* In my paper I recognized 15, but I no^ find that Astatotilapia cannot be 

 maintained as distinct from Ilaplochromis, several of tbe Lake Victoria species 

 having enhirged teeth at the ends of tbe priemaxillavies more or Jess developed and 

 not at all constant. 



