180 THE MARINE AND FRESH-WATER FISHES. 



SUB-CLASS CYCLOSTOMATA. 



Fam. Petromyzontidae. 



Petromyzon marinus, Lin. Sea Lamprey. Very r. Occasionally frequents 



R. Leven, and tributaries of L. Lomond ; ascending from sea in pairs to 



spawn. 

 P. fluviatilis, Lin. River Lamprey ; c. in most streams and lakes. Not 



migratory, and does not spawn in pairs, but promiscuously in groups of 



from 10 to 30 individuals. 







Fam. Myxinidae. 



Myxine glutinosa, Lin. Hag-fish, Rothesay ; said to be numerous off 

 Girvan, and destructive to line-fishes (H. B., p. 225). 



SUB-CLASS LEPTOCARDIL 



Fam. Cirrhostomi. 



Branchiostoma lanceolatum (Pallas). Lancelet, or Amphioxus ; nr. L. 

 Cumbrae (K.) ; bet. L. Cumbrae and Hunterston (Gray), (v. H. B. 

 p. 225, Landsborough, etc.) 



