THE SALMON. 



149 



eggs. Its power in this respect is very great. The 

 Lamprey belongs to the second order of fishes, the 

 Cyclostomata, or round mouthed. The fishes of this 

 order are in reference to their skeleton the lowest 

 among vertebrate animals. They are tough with no 

 scales, have a mottled skin and have no pectoral or 

 ventral fins. A long fleshy fold of skin runs round 

 the hind part of the body, but, as it has no rays, it 

 can scarcely be called a fin. The mouth is dotted 

 with small hook-like teeth. Instead of gills, the 

 breathing organs, the Lamprey has seven little sacs or 

 bags near the head, and each sac communicates with 

 the water by a separate opening. Professor Owen 

 says : " When the Lamprey is firmly attached, as is 

 commonly the case, to foreign bodies by means of its 

 suctorial mouth, it is obvious that no water can pass 

 by that aperture from the pharynx to the gills ; it is 

 therefore alternately received and expelled by the ex- 

 ternal aperture." The water, besides gaining admis- 

 sion by these seven canals to the branchial sacs, is let 

 in by the mouth if the animal so wills it, or by a 

 round hole observable on the top of the head. This 

 aperture has a direct communication with the pharynx. 

 Enormous quantities of the Lamprey used to be taken 

 in the Thames and sold to the Dutch fishermen for bait, 

 but by draining them off in such numbers they be- 

 came very scarce. 



The Salmonidas (genus Salmo), the most important 

 of British river fishes, include many species. The 

 chief of these is the king of river fishes, the Salmon 

 {Salmo salar). This fish is known in its various 

 stages by many names. Mr. Buckland considers the 



