426 FISHES CHAP. 



has two semicircular canals, and the eyes are not degenerate. 

 The pronephros is suppressed in the adult. The eggs are small ; 

 the segmentation is holoblastic ; and there is a larval meta- 

 morphosis. There is but one family. 



Fam. 1. Petromyzontidae. The family has a nearly world- 

 wide distribution. Most Lampreys are marine, although to a 

 greater extent in some species than in others, but all of them 

 seem to ascend rivers for spawning. The genus Petromyzon is 

 characteristic of the northern hemisphere, where it is repre- 

 sented by various species on the coasts and in the rivers of 

 Europe, West Africa, Japan, and North America. Three species, 

 widely distributed in Europe, occur in the British Isles, viz. : 

 the Sea-Lamprey (Petromyzon marinus), which may reach or 

 even exceed three feet in length, and is also found on the west 

 coast of Africa and on the Atlantic coast of North America ; 

 the " Lampern " or fresh-water Lamprey (P. flumatilis), abo'ut 1 8 

 inches long; and the Sand-Pride, Sand-Piper, or lesser fresh- 

 water Lamprey (P. planeri}, usually less than a foot in length. 

 Ichthyomyzon, Bathymyzon, Enter sphenus, and Lampetra, are also 

 northern forms, collectively distributed along the Atlantic and 

 Pacific coasts and in the rivers and great lakes of North 

 America. 1 Other Lampreys occur only in the southern hemi- 

 sphere. Geotria is common in the rivers of Chili, Australia, 

 and New Zealand ; and another genus, Mordacia, has a parallel 

 distribution, being found on the coasts of Chili and Tasmania. 

 A new genus and species from Chili has been recently 

 described under the name of Macr ophthalmia chilensis? 

 This Lamprey, which is only 107 mm. in length, has re- 

 markably large eyes (2'5 mm. in diameter), vertically com- 

 pressed gill -clefts, and a simple dentition resembling that of 

 Myxine. All Lampreys are carnivorous. They feed by attach- 

 ing themselves to the bodies of Fishes by their suctoral buccal 

 funnels, and then rasping off the flesh with their lingual teeth. 

 While thus engaged they are carried about by their victims. 

 Salmon have been captured in the Ehone with the marine 

 Lamprey attached to them. The Lamprey usually keeps near 

 the bottom, either swimming with a graceful serpentine move- 



1 Jordan and Evermann. op. cit. p. 9 et seq. 



2 Plate, Sitzungsb. d. Gesellsch. Naturforsch. Freunde Berlin, "No. 8, 1897, 

 p. 137. 



