LAMPEEYS. 



693 



large numbers the rivers of Europe, North America, and 

 Japan, and scarcely attaining a length of two feet; the 

 " Pride " or " Sand-Piper " or Small Lampern {P. hranchialis), 

 scarcely twelve inches long, the larva of which has been long 

 known under the name of Ammocoefes. 



Ichihyomyzon from the western cqfists of North America 

 is said to have a tricuspid maxillary tooth. 



MoEDACiA. — Dorsal fins two, the posterior continuous with 

 the caudal. The maxillary dentition consists of two triangular 

 groups, each with three conical acute cusps ; two pairs of serrated 

 lingual teeth. 



A Lamprey (if. mordax) from the coasts of Chile and 



Fig. 317. — Mouth of Mordacia mordax, closed and opened. 



Tasmania. This fish seems, to be provided sometimes with a 

 gular sac, like the following.^ 



Fig. 318. — Mordacia mordax. 



Geotria. — Dorsal fins two, the posterior separate from the 



' Fig. 317 is taken from a specimen in which the horny covers of the 

 dentition were lost, hence it does not represent acciu'ately the shape of the 

 teeth. 



