CYPBINID.E. 159 



CYPEINID^]. 



Mouth more or less protractile, toothless, bordered by the prsemaxillaries and the 

 maxillaries, or, more frequently, by the prsemaxillaries only. Parietal bones united in 

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

 symplectic present. Lower pharyngeal bones falciform, subparallel to the branchial 

 arches, provided with teeth arranged in one, two, or three series, and often remarkably 

 specialised. Ribs mostly sessile ; no parapophyses in the thoracic region ; epipleurals 

 and epineurals, mostly free, floating. Pectoral fins inserted very low down, folding like 

 the ventrals. Body naked or scaly. No adipose dorsal fin. 



The brain-case is produced forward to the nasal capsule. The branchiostegal rays 

 are reduced to three ; the branchiostegal membrane is usually more or less extensively 

 grown to the isthmus. 



Freshwater fishes feeding on vegetable substances or small animals, and dispersed 

 over the whole world with the exception of South America, Madagascar, Papuasia, 

 and Australasia. The species are exceedingly numerous, about thirteen hundred being 

 known. Two hundred and ten of these are African, falling into twelve genera, eight 

 of which are represented in the Nile system. 



Synopsis of the Genera. 



I. Cypkinin^e. — Barbels not more than two pairs; pharyngeal teeth large, in small number, 

 working against a sclerous plate attached to a ventral process of the basioccipital, which 

 extends under the anterior vertebrae ; air-bladder usually large and divided into an anterior 

 and a posterior part, not surrounded by a bony capsule. 

 A. Lateral line running along the middle o£ the side of the caudal peduncle ; anal fin with 

 5 or 6 branched rays ; suborbitals narrow, not covering the cheek. 

 Mouth inferior, crescent- shaped, with much developed lips forming a 

 sort of sucker and furnished on the inner side with a sharp cutting- 

 edge covered with a horny layer ; dorsal fin originating well in 



advance of the ventrals 1. Labeo. Cuv. 



Mouth inferior, transverse, crescent-shaped ; a more or less developed 

 suctorial disk on the chin, usually bordered by the lower labial 

 fold ; gill-openings restricted to the sides ; dorsal fin originating 

 well in advance of the ventrals 2. Discognathus, Heck. 



