THE LAMPREYS AND HAG FISHES 2929 



trils is situated in the middle of the head. The seven gill pouches open externally 

 by as many apertures on each side of the neck, but communicate with the pharynx 

 by a common opening to which the ducts of all converge. The intestine is fur- 

 nished with a spiral valve, and the eggs are minute. 



The true lampreys are characterized in the adult condition by having two dor- 

 sal fins, the hindmost of which is continuous with the caudal; and likewise by the 

 upper series of oral teeth consisting either of a doubly-cusped transverse ridge, or of 

 two closely -placed separate teeth; while the teeth on the tongue are serrated. The 

 genus appears to be represented by four species, which are confined to the coasts 

 and fresh waters of the Northern Hemisphere, ranging as far south as West Africa. 

 The largest of these is the sea lamprey, represented in the upper figure of our illus- 

 tration, which may grow to as much as a yard in length, and is common to Europe, 

 North America, and West Africa. On the other hand, the river lamprey, or lam- 

 pern, which at certain seasons ascends the rivers of Europe, North America, and 

 Japan in innumerable hosts, is somewhat less than two feet in length, and differs 

 from the last species in being uniformly colored, instead of marbled with black. 

 Still smaller is the small lamprey, also known as the pride or sandpiper, which is 

 likewise common to Europe and Western North America, and scarcely reaches one 

 foot in length; its coloration being uniform. The young of this form was long 

 regarded as a distinct genus, under the name of Ammoccetes; but its true nature 

 was discovered by watching the transformation into the adult. The larva, writes 

 Dr. Giinther, requires three or four years for its full development. At first the 

 head is very small, and the cavity of the mouth "surrounded by a semicircular 

 upper lip, the separate lower lip being very small. There are no teeth, but several 

 fringed barbels surround the mouth. The extremely small eyes are hidden in a 

 shallow grove; but there is a median single nasal opening, and seven gill openings, 

 as in the adult. The vertical fins form a continuous fringe, in which the later divi- 

 sions are more or less distinctly indicated." When open, the mouth of lampreys is 

 nearly circular in shape, but when closed forms a narrow slit. 



Much has still to be learned regarding the habits of lampreys, but it appears 

 that all the members of the present genus ascend rivers for the purpose of spawn- 

 ing, and that some of them pass the whole of their larval conditions in fresh waters. 

 They are all carnivorous, and in the adult state attach themselves by their mouths, 

 to the bodies of fishes, from which they rasp off the flesh with their horny teeth; 

 fish being not unfrequently met with bearing the scars of wounds thus inflicted, and 

 a salmon has been taken high up in the Rhone with a sea lamprey tightly adhering 

 to its side. Bathers have also been known to be attacked by the same species. Com- 

 monly keeping to the bottom, the sea lamprey may at times be seen swimming near 

 the surface with a serpentine movement of the body. In the Severn the capture of 

 this species lasts from February to May, while in the Thames the season is May and 

 June; but in the Scottish rivers the lampreys do not ascend till the end of June, re- 

 maining till the beginning of August. During the spawning season these fishes ex- 

 cavate furrows in the river bottoms for the reception of their eggs, and are said to 

 remove impeding stones by lifting them up with their sucking mouths. Being much 

 exhausted by the function of spawning, at its conclusion they make their way with 



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