CHONDROPTERYGII BRANCHIIS FIXIS. 231 



P. marinus, Lin. (The Sea Lamprey.) Two or three feet in length, marbled 

 with brown on a yellowish ground; two large approximated teeth on the 

 upper part of the maxillary ring. It ascends the mouths of rivers in the spring, 

 and is highly esteemed. 



P.fluvialis, Lin. (The River Lamprey.) From a foot to eighteen inches in 

 length ; silvery, blackish and olive on the back ; first dorsal very distinct from 

 the second ; two large separated teeth on the upper part of the maxillary ring- 

 Inhabits rivers, &c. 



j Linnaeus. 



Has but a single tooth on the upper part of the maxillary ring, which is alto- 

 gether membranous ; lateral dentations of the tongue strong, and arranged in 

 two rows on each side, so that the jaws of these fishes seem to be lateral like 

 those of insects or the nereides, which induced Linnaeus to place them in the 

 class of Vermes ; the rest of their organisation, however, is analogous to that 

 of the lampreys : the tongue also acts h'ke a piston, and the spine of the back 

 is in the form of a cord. The mouth is circular, and surrounded with eight 

 cirri ; in its upper margin is a spiracle which communicates with its interior. 

 The body is cylindrical, and furnished behind with a fin that surrounds 

 the tail. There are no vestiges of eyes. The eggs become large. These 

 singular animals pour out such an abundance of mucus through the pores of 

 their lateral line, that the water of the vases in which they are kept seems 

 to be converted into a jelly. They attack and pierce other fishes h'ke the 

 lampreys. 



They are subdivided according to the external orifices of their branchiae. 



