110 FISH GALLERY. 



an aquarium, and produce (apparently) fertile hybrids. The 

 Pomeranian Bream, Abramis buggenhagii, 1161, Cabinet-case 31, 

 is in all probability a hybrid between the Common Bream, 

 Abramis brama, 349, and the Roach, Leuciscus rutilus, 341. 

 The characters of the Pomeranian Bream are intermediate between 

 those of the Common Bream and the Roach, and the fish occurs in 

 localities where both the Common Bream and the Roach exist, in 

 England, Holland, Germany, Austria, &c. Bliccopsis erythroph- 

 thalmoides, 1168, Cabinet-case 31, a fish found in Holland and 

 Germany, is regarded as a natural hybrid between the Bream-flat, 

 Abramis blicca, 351, and the Rudd, Leuciscus erythrophthalmus, 

 335, and several other hybrids are recorded between species of 

 Leuciscus and those of Abramis, Alburnus and Chondrostoma. A 

 hybrid is also supposed to exist between the Roach and the Rudd, 

 and such a form has been described under the name Leuciscus 

 affinis. 



Katural hybrids, i. e. the offspring of different species pairing 

 in a state of nature, are extremely rare, but within the class of 

 Fishes there is yet another instance which may be regarded as 

 genuine, and that is the hybrid between the Turbot and Brill 

 (1167, Cabinet-case 31). The Grimsby fishermen occasionally 

 come across a fish which is intermediate in characters between the 

 Turbot and the Brill and which they call a hybrid. Since it 

 has been found possible in the artificial conditions of a marine 

 laboratory to fertilise the eggs of the one species of fish with the 

 sperms cf the other and to rear the young up to a certain stage of 

 development, it is very possible that they may be right. 



Bleak. The Bleak, Alburnus lucidus, 352, is a brilliant, silvery little 



fish, deriving its name from an Anglo-Saxon word meaning 

 " shining.'" In hot summer weather it hovers a few inches below 

 the surface of the water and glitters with silvery lustre in the 

 sunlight as it darts after flies or any small objects floating on 

 the surface. As in the Bream the anal fin has a long base, 

 and the hinder part of the abdomen ends below in a sharp 

 keel. The Bleak seldom grows to more than 4 or 5 inches in 

 length. 



Artificial From the scales of the Bleak is obtained a silvery powder, one 

 of the principal constituents of which is guanin, employed in. 



