32 Memoir Sears Foundation for Marine Research 



Key to Genera 



I a. Gill pouches on each side connect with exterior by single common aperture. 



Myxine Linnaeus, 1758, p. 32. 

 Atlantic and Pacific Oceans. 



lb. All gill pouches on each side open independently to exterior. 



2a. Gill openings on each side ( 1 6 in number) are close together. 



Paramyxine Dean, 1904. 



Japan. 



2b. Gill openings on each side ( 5-14 in number) separated by interspaces of consider- 

 able width. Eftatretus Cloquet, 1819.° 



Pacific Ocean. 



Genus Myxine Linnaeus, 1758 

 Hags 



Myxine Linnaeus, Syst. Nat., 1758: 650; type species, M. glutinosa Linnaeus. Atlantic Ocean. 



Generic Synonyms: 



Petromyzon (in part) Walbaum, P. Artedi Genera Pise. Emend. Ichthyol., Pt. 3, 1792: 500, for M. glutinosa; 

 not Petromyzon Linnaeus, 1758. 



GaUrobranchu! Bloch, Naturg. Ausland. Fische, Pt. 9, 1793: 66, pi. 413; type species, G. coecus Bloch. 

 Denmark, Sweden, Norway and Iceland. 



Muraenoblenna Lacepede, Hist. Nat. Poiss., 5, 1803: 652; type species, M. olivacea Lacepede. Straits of Ma- 

 gellan. 



Pholis Oken, Lehrb. Naturg., 5 (2), 1816: 122; alternative name for Myxine. 



Gasteobranchus Buckland, Nat. Hist. Brit. Fish., 1 881: 144; evident misspelling for Gastrobranchus. 



Generic Characters. Five or 6 gill pouches on each side opening to exterior by a single 

 aperture on ventral surface, close in front of origin of ventral finf old, the left-hand gill 

 opening, which receives the oesophago-cutaneous duct, being much the larger; fleshy flap 

 ("rostrum" or "labrum") overhanging nostril anteriorly; nostril close to tip of snout; 

 snout with 6 barbels, flanking both nostril and mouth ; each side with a series of large 

 mucous pores, segmentally arranged, extending from a short distance behind the mouth 

 rearward nearly to the caudal extremity. Characters otherwise those of the family and 

 order.* 



Range. Continental shelves and slopes of the North Atlantic in north temperate and 



5. This genus has been called most commonly Bdellostoma Miiller, 1835. It has been argued by Apstein (Sitzber. 

 Gesellsch. Naturf. Berlin, 1915: 187) and Rauther (in Bronn's Klassen, 6, Abt. i, Buch i, Lief 39, 1924: 685) 

 that it would be well to accept this as a nomen conservandum. But, awaiting action by the International Commis- 

 sion on Zoological Nomenclature, it seems to us wiser to use the older name. As Rauther points out, the original 

 description of Eftatretus was based by Cloquet (Diet. Sci. Nat., 1$, 1819: 135) on a combination of two species — 

 the Chilean dombei and an unnamed species from the South Seas. But even if Eftatretus were to be abandoned as a 

 generic name on that account, Bdellostoma is long antedated by Homea Fleming (Phil. Zool., 2, 1822: 374) and 

 by M'Murtrie's Heftatremus (Anim. Kingd. [after Cuvier], 2, 1831: 298). 



6. For an excellent account of the general morphology of Myxine, see Smitt (Hist. Scand. Fish., 2, 1895 : 1 196). 



