THE SHADS, THE EELS, AND THE LAMPREYS 301 



the teeth, the circular lip is fringed on the inside with a row 

 of short and slender tentacles. 



It may be asked, What is the purpose of this formidable 

 armature without jaws to work it ? The use to which it is 

 put has been well described by Couch : 



" For simply biting, as in other fishes, the teeth are 

 useless ; but when the breadth of the open mouth is brought 

 into contact with the surface of a fish on which the lamprey 

 has laid hold by producing a vacuum, these roughly-pointed 

 teeth are brought forward in a manner to be able to act on it 

 by a circular motion, and a limited space on the skin of the 

 captive prey is thus rasped into a pulp and swallowed, so that 

 a hole is made which may perhaps penetrate to the bones, from 

 the torture of which the utmost energy of the victim cannot 

 deliver it." 



He mentions that he has found lampreys thus feeding upon 

 the living bodies of mackerel, gurnard, coal-fish, cod, and 

 haddock ; and Giinther mentions that salmon have been taken 

 far up the Rhine with these formidable creatures fixed to them 

 and boring into their flesh. 



Lampreys ascend the rivers from the sea in spring in 

 order to deposit their spawn. It is stated that at this season 

 a fimbriated crest rises on the back, probably only of the 

 male, between the head and the first dorsal fin, and a corre- 

 sponding adornment appears on the under part of the tail, 

 behind the vent. Such a feature has its analogy in the nuptial 

 livery of some of the aquatic reptiles with which some 

 naturalists have been inclined to associate lampreys more 

 closely than with fish. After spawning, lampreys exhibit 

 much exhaustion, and deteriorate in condition in as marked 

 a degree as do salmon. It has been asserted that they all 

 die immediately after spawning, but of this there is no satis- 

 factory evidence forthcoming ; but it may be observed that 

 eels are suspected of being capable only of a single effort at 

 reproduction. 



