FISHES 



7 



6. Lampetra Gray. Teeth very few, there being usually 3 enlarged 

 two-cusped laterals on each side of the 

 mouth; supraoral lamina with 2 separated 

 cusps, joined by a bridge: 3 American species. 



L. ayresii (Giinther). Length 350 mm.; 

 dorsal fins separated; 63 to 70 muscle seg- 

 ments between gills and anus; teeth strong 

 and sharp; infraoral lamina with 6 to 9 cusps; 

 anterior portion of buccal disc with many 

 teeth: coasts and streams of Europe, Asia 

 and western North America from San Fran- 

 cisco to Puget Sound. 



7. Okkelbergia Creaser and Hubbs. 

 Similar to Lampetra: 1 species. „ „ , . 



f '- Fig. 12. — Buccal funnel of 



0. lamotteni (LeSueur) [L. CEpVptera LethenUron appendix {from 



Abbott) (Fig. 13). Length 120 mm.;' teeth p^^'^'^^ of Illinois). 

 much reduced in number and size; infraoral lamina with a crenulated 

 crest and without distinct cusps; lateral teeth sometimes unicuspid 

 and more or less obsolescent; anterior portion of buccal disc with 



Fig. 13. — Buccal funnel of Okkelbergia lamotteni {from Creaser b^ Hubbs). 



usually 4 teeth; 54 to 60 muscle segments between gills and anus: in 

 the Ohio and Potomac River basins. 



