50U I'Erui.MV/uNTiu.v:. 



the middle of the upperside of the head. The nasal 

 duct terminates without peiforatin^i^ the palate. Seven 

 branchial sacs and apertures on each side behind the 

 head. The inner branchial ducts terminate in a sepa- 

 rate common tube. Intestine with a spiral valve. 

 Eggs small. 



The larvce without teeth and \\'\i\\ a single con- 

 tinuous vertical fin. 



Lampreys. Inhabitants of the fresh waters and coasts of the tom- 

 lieratv rep:ions of botli hemispheres. Suck tliemselvcs fust to other 

 fish, and feed by scraping off their flesh. 



ISiinopsis of the Genera. 



A. Tlio second dor.^al fin continuous with the caudal. 



Maxillary tootfi bicuspid 1. JV-trnmyzim. p. 500. 



]\Ia.\illary tooth tricuspid 2. IrhtJijfontijzou, p. 500. 



Two tricuspid groups of maxillary teeth . . '\. Murdacat, p. 507. 



V,. The second dorsal fin separate from the caudal. 



Maxillary lamina four-lobed 4. Geotria, p. 508. 



1. PETROMYZON* 



Petromyzon, Artcdi, Gen. p. 04. 



♦ I. Petromyzon argenteus, Kirtland, Host. Journ. Nat Kisf. iii. 1842, pi. 4. 



fi^. .3. — 15ig Miami, Ohio. — Dor.s:il fin rpprLsonted high and continuou.s, 



witli a yery shallow depre.ssion instead of the usual separation of the 



dorsal fins. 

 2. lamottenii, (Lesueur) Bchay, Fish. Nfw YorJ:, p. 382, pi. 79. 



Cg. 24'J. — North America. — Perhaps a small P. marinvs. 

 3. appendix, Ihkai/, I. c. p. 381, pi 04. fig. 211. — Xew York.— 



Vro\>iih\y=^ P. hranchudis; the anal appendage is the genital tube visible 



in Lampcrus during th(^ breeding-season. 



4. Ammoca'tes concolor, Kirfland, Bust. Joitrn. 2\at. Hist iii. p. 473, pi. 27. 



fig. 1. — Mahoning and Scioto Rivers. 



5. bicolor, Lr.suciir, Tra»s. Amer. Phil. Soc. i. p. .380; Dei-ay I.e. 



p. 3S.'i, pi. 7'.'. fig. 248. —Connecticut Eiver. 



6. unieolor, Uc/ca//, I. c. p. .■'.83, pi. 79. fig. 2.')0. -Lake Cliamplain. 



7. boreal is, Ajinssi::, Ln Ice Super, p. 2.'j2. — Lake Superior. 



8. ciLTulcus, i'hi/ijijti. JVicffm. Arch. 18.38, p. 300. — Valdivia. 



9. landbceki, Philipjii, I. c p. .307. — Valdivia. 



10. Cliilopterus, l'liili]>pi. I. c. p. .308. — Valdivia. — This .suppo.scd genus 



[wliicli is evidently a larval {Ammocoefei) form] is characterized thus: 

 Corpus vermiroriiie, eaeuin. Os edentulum. Labia duo distincta, in- 

 ferius fonnaiii tiibi diniidiati brcvis referCns ; sujjerius mains. Irans- 

 versutn, semiorbicularo, lateribus liboris involutis labrum inl'crius am- 

 pleetens. Pinna dor.salis unica cum eaudali conlluens. 



11. Annnoca-les .Tpvptera, Abb(jU, I'roc. Ac. Nuf. Sc. Philwl. ISOrt y .327. — 



Ohio. 



12. Pftroniyzon (mariniis) caiiitsehal ir-us, Pa!L Zooi/r. /i*o.«.'-.-^-l.v. iii. p ('.7. 



Kamstseli:itl<M. 



