;"00 PElRUMYZOMID-E. 



the middle of the upperside of the head. The nasal 

 duct terminates without perforating- the palate. Seven 

 brancliial sacs and apertures on each side behind the 

 head. The inner brancliial ducts terminate in a sepa- 

 rate common tube. Intestine with a spiral valve. 

 Eggs small. 



The Jarvce without teeth and with a single con- 

 tinuous veitical fin. 



Lampreys. Tiilialiitants of the fresh waters and coasts of the tem- 

 porai:e regions of botli hemispheres. Suck themselves fast to other 

 fish, and feed by scraping off their flesh. 



iSi/nopsis of the Genera. 



A. The second dovsal fin coutinuoui witli the caudal. 



Jfaxiliary tooth bicuspid 1 . Petroini/zvn, p. -500. 



IMaxillavy tooth tricuspid if. Irhthijinnyzon, p. 506. 



Two tricuspid groups of maxillary teeth . . .'>. Murducia, p. 507. 



B. The second dorsal fin separate from the caudal. 



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



1. PETEOMYZON*. 

 Petromj'zon, Artcdi, Gen. p. 04. 



* ]. Petromyzon argenteus, Kirtland, Boat. Journ. Kuf. Hist. iii. 1842, pi. 4. 

 fig. 3. — Big Miami, Ohio. — Dorsal fin rpprjseuted high and continuous, 

 with a very shallow depression instead of the usual separation of the 

 dorsjJ fins. 



2. lamottenii, {Lesiicnr) BcJcai/, Fish. New York, p. 382, pi. 79. 



fig. 240. — North America. — Perhaps a small P. marinus. 



3. appendix, Dekaij, I. c. p. 381, pi G4. fig. 211.^New York. — 



P robably = P. branchialis ; the anal appendage is tlic genital tube visible 

 in Lamperns during the breeding-season. 



4. Ammooa'tes cjncolor, Kirtland, Bost. Journ. Nat. Hist. iii. p. 473, pi. 27. 



fig. 1. — Mahoning and Scioto Rivers. 



6. bicoloi", Lesueur, Irons. Amer. Phil. Soc. i. p. 386 ; Bekay I. c. 



p. 383, pi. 79. fig. 248. — Connecticut River. 



6. unicolor, Dckat/, I. c. p. 383, pi. 79. fig. 250. — Lake Champlain. 



7. boi-eahs, Agassiz, Lake Super, p. 252. — Lake Superior. 



5. caTuleus, Phdip-pi. Wiegin. Arch. 1858, p. 306. — Valdivia. 



'J. landbecki, I'hilippi, I. c. p. 307.— Valdivia. 



10. C'hilopterus. Philippi, I. c. p. 308. — Valdivia. — This supposed genus 



[wliich is evidently a larval (JwmoccBi'es) form] is characterized thus: 

 (.'orpus vermiCorme, c;ccum. Os edentulum. Labia duo distincta, in- 

 ferius formani tubi dimidiati brevis referens ; superius mains, trans- 

 v"rsuni, seiiiiorbiculare, lateribus liberis involutis labrum inferius am- 

 pleelens. Pinna dorsalis unica cum caudali confluens. 



11. Ammocccics a?pyptcra, Abbott, Proc. Ac. Nat. Sc. Philad. 1860. p. 327. — 



Oliio. 



12. Petromyzi.u (niai'inus) camtschatieus. Pall. Zooijr. Bofs.-As. iii. p 67. — 



Kani>tpcliatkfi. 



