144 



NATURAL HISTORY. 



metamorphosis and attain complete development. In the adult, as in the young, there is only a 

 single nostril on the upper side of the head. There are seven branchial sacs. The intestine has a 



spiral valve. 



THE SEA LAMPREY.* 



The Sea Lamprey commonly attaches itself by the mouth to stones and rocks. The mouth is full 

 of small teeth. The maxillary teeth are two in number and united together; in the lower jaw there 

 is a single crescent-shaped tooth-plate, with from seven to nine cusps. The other teeth are arranged in 

 rows, which cross each other obliquely, and more or less cover the whole surface of the mouth and 

 throat ; some of them are bicuspid. They often attach themselves to the bottom of a boat or ship, 

 and the air is so perfectly exhausted that a fisherman is sometimes unable by sheer strength to pull the 

 fish off. Couch records that the young Lamprey often attaches itself to the Mackerel, Gurnard, Coal- 

 fish, Cod, and Haddock, rasping considerable holes in the flesh with its suctorial teeth, and he states that 



SEA LAMPllEY. 



instances have come under his notice in which wounds evidently made in this way have afterwards 

 healed. The spawning time of the Sea Lamprey varies a little in different countries, but in England 

 the spawn is deposited in April and May, when the fish ascend livers. They are then in the finest 

 condition, and are caught at night. The male and female fish prepare a groove in the bottom of the 

 river, in which the eggs are placed so as to be covered with sand. Yarrell states that the roe escapes 

 by a membranous sheath, the internal face of which has five apertures. The fish has always been 

 valued for food. In England it is chiefly taken in the Severn, though sometimes met with in the 

 Thames and many other rivers. It is found in the Rhine as far up as Basle, in nearly all the rivers 

 of France, in the Rhone, and the Italian rivers which empty into the Adriatic and the Mediterranean. 

 According to Siebold, it occurs on all the coasts of Europe excepting those of the Black Sea. It 

 ranges southward to the west coast of Africa, and is found in North America. The Sea Lamprey 

 usually measures less than three feet in length. 



The first dorsal fin is well separated from the second dorsal fin. Both ai-e placed on the hinder 

 part of the body. The colour is a greenish-brown, marbled on the sides and back with darker tints of 

 brown and green. It swims with lateral movements of the body, but commonly remains on the 

 bottom. The mouth shuts laterally instead of vertically. 



* Petromyzon nuirinus. 



