CHAEACINIDiE. 97 



OSTAEIOPHYSL 



CHARACINIDiE. 



Mouth non-protractile, usually bordered by the prsemaxillaries and the maxillaries, 

 rarely by the prse maxillaries only; jaws usually toothed. Parietal bones united in a 

 sagittal suture or separated by a fontanelle ; opercular bones well developed ; symplectic 

 present. Pharyngeal bones normal, with small teeth. Ribs mostly sessile ; no para- 

 pophyses in the thoracic region ; epipleurals and epineurals mostly free, floating. 

 Pectoral fins inserted very low down, folding like the ventrals. Body covered with 

 scales. An adipose dorsal fin often present. 



A very generalized group *, confined to the fresh waters of Africa and Central and 

 South America. The species number about 500, of which only one-fifth are African. 

 Of the twenty African genera only eight are represented in the Nile system. 



Synopsis of the Genera. 



I. Hydeocyonin^e. — Teeth strong ; maxillary well developed ; scales not ciliated ; lateral line 



nearer ventral than dorsal outline. 



Teeth compressed, unicuspid, in a single series 1. Hydrocyon, Cuv. 



Teeth in two series in the upper jaw, pluricuspid. the inner with 

 obliquely truncated or molariform excavated crowns ; mandibular 

 teeth pluricuspid, in a single series followed behind by a pair of 

 conical teeth 2. Alestes, M. & T. 



Teeth in two series in the upper jaw, compressed and pluricuspid ; 

 mandibular teeth similar, followed behind by a pair of conical 

 teeth 3. Micralestes } Blgr. 



II. Ichthyoborin^e.— Teeth strong ; maxillary much reduced; scales ciliated; lateral line 



median. 

 Large canine teeth anteriorly ; upper jaw freely movable upwards ; 



mouth large 4. lehthyobomis, Gthr. 



* On the anatomy, cf. Sagemehl, Morphol. Jahrb. x. 1885, p. 102, and xii. 1887, p. 307, and Eowntree, 

 Tr. Linn. Soc, 2nd ser. Zool. ix. 1903, p. 47. 



