Fishes of the Western North Atlantic 33 



subarctic latitudes, including the Mediterranean (Adriatic) in moderate depths; coasts of 

 southern Argentina, Chile, Japan, and South Africa; Gulf of Panama in deep water (1,335 

 meters), the latter being the only locality where the genus is known to occur in tropical or 

 subtropical latitudes. 



Species. The representatives of the genus fall in two well defined groups, according 

 to whether the first three lingual teeth of the anterior row are fused at the base, or only the 

 first two, which is more usual. One member of the first of these groups, M. circifrons, is 

 further set apart from all others in the genus by the fact that it has only five pairs of gill 

 sacs. Unfortunately this feature is not apparent from the exterior, and other characters 

 that have been used to separate supposed species, such as relative length of head and 

 number of mucous pores, overlap to such an extent that it is doubtful how many of the 

 named forms will finally stand. For further discussion, see p. 38. 



Key to Species of Myxine 



I a. First 3 lingual teeth in anterior series fused together at base. 



2a. Lingual teeth j| ; head nearly or quite 33.3 % of total length. 



circifrons Ga.Tma.n, 1899.' 

 Gulf of Panama. 



2b. Lingual teeth onlyi^ or fewer; head not more than 29% of total length. 



3a. 26 or 27 mucous pores anterior to gill openings, and 12 or 13 posterior to 

 anus. garmani Jordan and Snyder, 1 90 1 . 



Japan. 



3b. Only 22 mucous pores anterior to gill openings and 9 posterior to anus. 



tridentiger Gzrmzn, 1899. 

 Straits of Magellan, 

 lb. Only 1st 2 lingual teeth in anterior row fused together at base. 



4a. Lingual teeth only | . faucidens Regan, 1 9 1 3. 



Japan. 

 4b. Lingual teeth ^ or more. 



5a. 10- 1 1 teeth in anterior series in adult. a finis Giinther, 1 870. 



Straits of Magellan. 



5b. Not more than 7-9 teeth in anterior series in adult. 



glutinosa Linnaeus, 1758, p. 34.* 

 Both sides of North Atlantic. 



7. This species is set apart from all others of the genus by the fact that it has only five pairs of gill sacs. This, how- 

 ever, is not apparent externally. 



8. Including cafensis Regan, 1913, South Africa, and australis Jenyns, 1842, Chile and southern Argentinaj these 

 species and glutinosa so overlap one another in the' number of teeth and mucous pores and in the relative length 

 of head that we have not been able to construct a key by which individual specimens could be identified with cer- 

 tainty. Neither can the presence of seven pairs of gill pouches in cafensis be regarded as a unique specific charac- 

 ter, since occasional specimens of glutinosa may have this same number (footnote 11, p. 35). Information on 

 the number of teeth ( jj ) and gill pouches of cafensis, which was not included in the original description of 

 the species (Regan, Ann. Mag. nat Hist., [8] n, 1913: 398), has been obtained subsequently (Barnard, Ann. 

 S. Afr. Mus., 31 [i], 1925: 15). 



