PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 71 



The species of Oncorhynchus at present admitted by Dr. Gill and 

 myself may be briefly compared as follows : — 



a. Body more elongate, heavier forward and less compressed than iu the next; jaws 

 in the adult males very unequal ; the lower jaw prolonged and hooked 

 upwards ; the upper jaw still more elongate and curled over the tip of the 

 lower, the profile of the forehead being concave when viewed from the side; 

 teeth of the premaxillaries and of the tip of the lower jaw greatly enlarged 

 and hooked (Subgenus Oncoi-hynchus.) 



b. Scales very small, in more than 200 transverse rows ; smaller on caudal peduncle 

 than on flanks ; form much distorted in the adult males, the fleshy hump at the 

 shoulders being greatly developed, and the caudal peduncle slender and rather 

 elongate ; the jaws greatly prolonged and curved ; size small. (Pacific coast 

 and streams, Washington to Kamtschatka.) corbuscha.* 



hi). Scales medium, in about 170 (155 to 180) transverse rows; form distorted, but 

 less so than in the i^receding, the fleshy hump considerably developed in the 

 males, and the jaws greatly elongated and hooked; branchiostegals about 16. 

 (Pacific coast and streams, Oregon to Kamtschatka.) KEXA.t 



bhb. Scales large for the genus, iu about 133 transverse rows, 

 c. Form elongate, not greatly compressed, the greatest depth in advance of the 

 middle of the body ; the males with the caudal peduncle rather slender, and 

 with a well-marked fleshy hump, and with the jaws much elongated and dis- 

 torted ; caudal fin feebly forked ; branchiostegals about 13. (Pacific coast 



and streams, California to Kamtschatka.) nerka.j: 



cc. Body elongate, compressed, the greatest depth (in female and immature speci- 

 mens at least) being just under the dorsal fin; depth of body one-fourth of 

 length, or a little more ; head moderate, rather bluntly pointed ; less distorted 

 in male specimens than in the preceding species; maxillary shortish, curved, 

 reaching somewhat beyond eye; caudal fin more or less forked ; branchioste- 

 gals 15 or 16. (Coast and streams, California to Alaska.) quinnat. 



aa. Body oblong, very strongly compressed, the dorsal region much elevated ; a nearly 

 even slope from the snout to the base of the dorsal fin ; dorsal fin unusually 

 far back, the first ray being behind the middle of the body ; head long, deep, 

 compressed, but still wide ; mouth extremely large and very oblique ; the jaws 

 about equal in the females ; in the males, the lower jaw protruding beyond the 

 upper, which is curled up like the snout of a snarling dog, showing the 

 enlarged canines, the premaxillaries never hooking over the lower jaw, as is 

 the case with Oncorhynchus proper ; dentition as in typical Oncorhynchus. 



(Subgenus Hypsifario Gill.) 



* Oncorhynchus gorbuscha (Walb.) Gill & Jordan. — Gorbnscha, Pennant, Arctic 

 Zoology. — Salmo goi-buschajWaihaum, Artedi Gen. 1792. — Sahno gibber, Bloch, Schneider, 

 Ichthyologia, 1801. — Salmo proteus, Pallas, Zool. Rosso-Asiatica, 1811. — Salmo gibber, 

 Suckley, 1861. — Oncorhynchus gorbuscha, Jordan, Man. Vert. ed. 2d, 1878. 



t Oncorhynchus keta (Walbaum) G. & J. — Kefa vel kayko, Pennant, Arctic Zool- 

 ogy. — Salmo keta vel kayko, Walbaum, 1792. — Salmo keta vel kayko, Bloch, Schneider,, 

 1801. — Salmo lagocephalus, Pallas, 1811. — <Sa/mosco»7eri, Richardson, 1836. — Salmo conflu- 

 entus, 1861. — Oncorhynchus keta, Jordan, Man. Vert. ed. 2d, 1878. 



I Oncorhynchus nerka (Walb.) Gill & Jor. — Narla, Pennant, Arctic Zoology. — 

 (SaZmo «e/-fca, Walbaum, 1792. — Salmo hjcaodon, Pallas, 1811. — Salmo japonensis, Pallas,. 

 1811. — ? Salmo paucidens, Richardson, 1836. — Salmo consuetus, Richardson, Voyage of the 

 Herald, 1854. — Salmo dermatinus, Richardson, /. c. 1854. — Salmo cants, Suckley, 1861. — 

 Salmo cooperi, Suckley, 1861. — Salmo scouleri, Suckley, 1861, (not of Rich.). — Salmo trun- 

 catus, Suckley, 1861. — ? Salmo richardi, Suckley, 1861. — Oncorhynchus hjcaodon, GUnther,, 

 1867. — Oncorhynchus nerka, Jordan, 1878. 



