292 THE RIVER-SIDE NATURALIST. 



Petromyzon (Stone-Sucker) has two dorsal fins, the 

 posterior joined with the caudal ; two teeth in the jaws, 

 placed close together, the lingual teeth serrated. 



The SEA- LAMPREY (Petromyzon marinus) ascends the 

 rivers to spawn in the spring, and is caught in considerable 

 numbers in the estuary of the Severn and the river itself. 

 They were formerly, and still are occasionally, found in 

 the Thames, also in some of the rivers in Scotland and 

 Ireland. Lampreys are said to die after spawning. 



The LAMPERN or SILVER LAMPREY (Petromyzon fluviatilis), 

 also known as Lampron or Lamper Eel, Nine Eyes, Seven 

 Holes, Spanker Eel, Say-Nay, &c., is very common in 

 many of the rivers in England, Scotland, and Ireland, more 

 particularly in the Thames, the Severn, the Kennet, the 

 Dee, the Trent, the Tweed, and many others. At Tewkes- 

 bury, on the Severn, there is a large manufactory for 

 potting lamperns. 



The lampern spawns from April to June. Sometimes 

 they go in pairs, sometimes in numbers, to the breeding- 

 ground, while the male and female act together in removing 

 stones in order to prepare the spot. We have seen this 

 process going on in the Kennet, and the size of the stones 

 moved by these small creatures is extraordinary. 



Their food consists of insects, worms, and the flesh of 

 dead fish. Day says they affix themselves to living fish, 

 among which they are accused of doing much injury. 

 Thomson says he received one which was taken adhering 

 to a large trout. 



The adult fish is usually from twelve to fifteen inches in 

 length, the body slender, cylindrical for two-thirds of its 

 length, then compressed to the end of the tail ; head 

 rounded, with a single aperture on the crown. The lips 

 surrounding the mouth have a continuous row of small 

 points on their margin ; the back is furnished with two 

 rather elongated dorsal fins. 



