212 BRITISH FRESHWATER FISHES 



three and a half times in the length to the base 

 of the caudal fin. The mouth is terminal and 

 oblique, with the jaws equal anteriorly. The dorsal 

 fin, of three simple and nine branched rays, is 

 above the interspace between the pelvic and anal 

 fins, and the branched rays in the last-named 

 number thirteen ; the free edge of the dorsal and 

 anal fins is concave. The abdomen between the 

 pelvic fins and the vent is compressed to a ridge, 

 which is crossed by the scales except posteriorly. 

 The Roach parentage is conclusively established 

 by the pharyngeal teeth, which as in that species 

 are hooked, slightly denticulated, set in a single 

 series, five on one side and six on the other. There 

 are forty-three scales in the lateral line, eight in 

 a transverse series above it, and four between it 

 and the base of the pelvic fins. 



The Chub x Bleak hybrid has been recorded from 

 various continental localities, and is also represented 

 in the British Museum collection by specimens from 

 the Thames at Staines, the Mole at Moulsey, and 

 a reservoir near Oundle. In these fishes the body 

 is elongate, as in the Chub and Bleak ; the mouth 

 is terminal and oblique, with the jaws equal an- 

 teriorly ; the dorsal fin, composed of three simple 

 and eight branched rays, is situated above the 

 interspace between the pelvic and anal fins, whilst 

 the branched rays in the anal fin number ten to 

 thirteen, more than in the Chub, which has eight 

 or nine, and fewer than in the Bleak, which has 

 from fifteen to twenty. The belly behind the 

 pelvic fins is compressed to a sharp edge, but the 

 scales pass over this except posteriorly. 



The features so far described show that the 



