5 54 Me^noir Sears Foundation for Marine Research 



For a recent account of the occurrence of the New Zealand smelt, with illustrations, 

 see Graham (j2 : 113). The so-called "herring smelt" of the northern North Atlantic 

 belongs to the Argentinidae, a family differing widely from the true smelts in having 

 a very small mouth and a structure in the intestine reminiscent of the spiral valve of 

 elasmobranchs but probably not homologous with it (Part 4). 



Key to Genera of Osmeridae^ 



I a. Scales small, in 170—220 transverse series. Mallotus Cuvier 1829, P- 573- 



I b. Scales large, fewer than 80 along lateral line. 



2 a. Teeth on vomerine bone (roof of mouth) and on tip of tongue large, canine-like. 

 3 a. Pelvic fins inserted under or posterior to origin of dorsal fin. 



Osmerus Lacepede 1803, below. 

 3 b. Pelvic fins inserted definitely in advance of origin of dorsal fin. 



4a. Head, as seen from above, sharply pointed; gill covers only weakly 

 striated; gill rakers 10 or 1 1 + 22— 26 on first arch; anal fin with only 

 15—17 rays. Allosmerus Hubbs 1925. 



Coast of northern California. 

 4b. Head, as seen from above, bluntly rounded; gill covers strongly 

 striated; gill rakers only 4-6 + 13— 16 on first arch; anal fin with 

 20—22 rays. Thaleichthys Girard 1858. 



Alaska to Oregon. 

 2 b. Teeth on roof of mouth small, not canine-like. 



5a. Pectoral fins considerably shorter than head; base of anal fin shorter than 

 head, its maximum height less than height of dorsal ; upper jaw reaching 



only a little past anterior edge of eye. Hypomesus Gill 1862. 



Alaska to middle California; 



also Kamchatka and Japan. 



5b. Pectoral fins about as long as head; base of anal fin about as long as head, 



its vertical height considerably greater than height of dorsal; upper jaw 



reaching back as far as rear margin of eye. 



Spirinchus Jordan and Evermann 1896. 

 Pacific coast of America, Middle California to Alaska. 



Genus Osmerus Lacepede 1803 

 Smelts 



Osmerus Lacepede, Hist. Nat. Poiss., 5, 1803: 229; type species, Salmo epcrlanus Linnaeus, Syst. Nat., ed. 10, 

 J, 1758: 310. "Habitat in Europa." 



5. The so-called "ghost smeh," Therobromus callorhtni Lucas 1898, which is known only from bones found in the 

 stomachs of fur seals, has been included in the Osmeridae by Jordan, et al. {$2: 68). But Hubbs has suggested that it 

 may not be an osmerid at all {^j-.^tj, ftn.), while Chapman has concluded definitely that it is not {11 : 295). In any case, 

 it cannot be included in this Key for want of information about its external features. 



