19G THE FRESH-WATER FISHES OF EUROPE. 



where the stream flows swiftly. Bloch states that the whitish eggs number 

 nearly 8,000. Fatio found them to be as large as millet- seed, and of a 

 greenish tinge. Heckel and Kner mention that this species spawns in 

 August in the Danube, but the statement is open to some doubt in face 

 of the spring spawning in other parts of Europe, though it is well known 

 that spawning may be delayed by unfavourable weather. At the breeding 

 season the male acquires the conical warts which are usual in Cyprinoids ; 

 but in the female they are limited to the skull and the sides of the snout. 

 The colours then become more intense, and, according to Benecke, in North 

 German specimens the abdomen becomes black. When the spawn is being 

 deposited, the fish grow extremely active, pressing against each other, and often 

 make a rustling noise with the fins as they jump along the surface of the water. 



The Nasling in Switzerland is infested with many entozoa, but in the 

 Neckar Dr. Giinther found it to be free from parasites. 



The bones of the face are wider than in other Cyprinoids. The infra-orbital 

 bones are small, owing to the size of the second, third, and fourth elements 

 in the orbital ring, and a fifth bone unites these to the skull. The pharyngeal 

 bones, in harmony with the teeth they carry (Fig. 106), are thick and strong. 

 There are twenty-seven thoracic vertebrae, and twenty-one in the tail. There 

 are twenty-one pairs of ribs. 



The intestine is nearly three times as long as the entire fish. After 

 making a fold in the lower part of the abdomen, it forms a spiral of 

 several coils, and then runs back to the vent. The liver has two lobes, 

 and surrounds the intestine. The gall-bladder is long and yellow, and situate 

 in the upper part of the right lobe. The milt is blood-red. The posterior 

 portion of the air-bladder is twice as large as the anterior part. 



This species is very variable, but the varieties are limited in their geo- 

 graphical range. Thus the coffee-coloured variation already referred to as 

 found in the Moselle and Neckar, originally distinguished as Ckondrostoma au- 

 ratus, and popularly known in Germany as Gold Nose and Golden Mackerel, 

 varies still further at Trier. The back becomes golden olive-brown, and 

 the abdomen is dull brown. All the scales are broadly bordered with pale 

 golden-green. White scales in patches are scattered over the body. The 

 dorsal fin and upper lobe of the caudal are golden green, and the other fins 

 are red, as in the ordinary Nasling. Both the dorsal and anal fins have 

 fifteen rays. 



A bluish variety, Chondrostoma cwrulescens, has been recorded in Western 

 France by Blanchard, from the Rivers Doubs and Ognon. The whole body 

 has a blackish-grey tint, with a bright steel-blue iridescence. Below the 

 lateral line the scales are spotted with large black points, and similar spols 



