OSTARIOPHYSI 



583 



Homaloptera in habit, with two gill-clefts on each side, an upper 

 and a lower, a tadpole-like mouth without barbels, and a small, 

 free air-bladder, should probably be regarded as the type of a 

 fifth sub-family. 



Many of the genera of the Cyprininae are partly founded on 

 the shape and the disposition of the 

 pharyrigeal teeth, which, adapted to 

 various requirements, may be conical, 

 hooked, spoon-shaped, molariform, etc., 

 etc. The importance attached to the dis- 

 position of tlu-se teeth in one, two, or 

 three series for the definition of genera, FIG. 352. Lower pharyngeais of 

 has been rather exaggerated. 1 Earblls tropidokpis. 



The Cyprinids constitute the majority of the freshwater fishes 

 in Europe, Asia, and North America ; they are comparatively 

 few (about 100 species) in Africa, where they coexist with the 



FIG. 353. Labeo falcifer, from the Congo, showing nuptial tubercles on the snout. 



J nat. size. 



Characinids. Some, like the Carp (Cyprinus carpio) and the 

 Tench {Tinea vulgaris), are sluggish, except during the breeding 

 season, when they show great excitement and indulge in leaps 

 out of the water; others, like the Bleak (Alburnus lucidus) are 

 constantly on the move in large shoals near the surface ; whilst 

 others again, like the M'Biriki of Lake Tanganyika (Sarbics 

 tropidolepis), behave after the manner of Salmon and Trout, 



1 For an illustrated account of the principal types of pharyugeal teeth, cf. 

 Heckel, Russeggers Reisen, i. p. 1001, pi. i. (1843). On their variations in certain 

 European species, cf. Heincke, Leuckart Festschrift, p. 85 (1892). 



