486 Bulletin 4J, United States National Museum. 



9. The number of vertebr:P. 



10. The number of pyloric ccpca. 



11. The number of gill rakers. 



Salmo. Salmon; species auadromous : 

 a. The vomerine teeth little developed, those on the shaft of the bone few and deoiduous ; 

 scales largo, abont 120 in the lateral line ; no hyoid teeth ; sexual differences strong ; 

 breeding males with the lower jaw hooked upward, the upper jaw emarginate or per- 

 forate to receive its tip. Size large. salar, 778. 

 Tkutta (Low Latin Tnilla, French Tniile, hence Trout). Trout; species not auadromous or only 

 partially so : 

 aa. The vomerine teeth well developed, those on the shaft of the bone numerous, persistent, 

 arranged in one zigzag row, or in two alternating rows ; sexual differences less 

 marked, but similar in general character to those seen in the salmon. 

 b. Scales always small, usually about in 160 (150 to 200) cross series ; a large deep red or 

 scarlet dash on each side concealed below the inner edge of each dentary bone, this 

 rarely obsolete ; lower fins red or j'ellowish ; usually no red lateral band ; mouth 

 large, the maxillary If to 2j in head ; hyoid teeth (on hypobranchial of second gill 

 arch) usually present, but very small ; size various. mykiss, 779. 

 bb. Scales moderate, usually about in 150 cross series (130 to 180); no red dash on denla- 

 ries ; a reddish lateral band usually present ; form rather stout ; mouth moderate, 

 the maxillary 2 in head ; hyoid teeth wanting so far as known ; size very large. 



GAinDNERI, 780. 



bbb. Scales typically large, in 120 to 130 cross series, but varying from 115 to 180; usually 

 no red on dentaries ; a red or j'ellow lateral band; form stout; mouth small, 

 the maxillary 2 to 2^^ in head ; no hyoid teeth ; size rather small. 



inii)Er.s, 781. 



Subgenus SALMO. 

 778. SALMO SALAR, Linnreus. 

 (Common Atlantic Salmon.) 

 Head 4; depth 4. B. 11 ; D. 11; A. 9; scales 23-120-21; vertebrre 60; 

 pyloric c(pca about 65. Body moderately elongate, symmetrical, not 

 greatly compressed. Head rather low. Mouth moderate, the maxillary 

 reaching just past the eye, its length 2i to Sin head ; in young specimens 

 the maxillary is proportionately shorter. Preoperculum with a distinct 

 lower limb, the angle rounded. Scales comparatively large, rather largest 

 posteriorly, silvery and well imbricated in the young, becoming embed- 

 ded in adult males. Coloration in the adult, brownish above, the sides 

 more or less silvery, with numerous black spots on sides of head, on body, 

 and ou fins, and red patches along the sides in the males ; young speci- 

 mens (parrs) with about 11 dusky crossbars, besides black spots and red 

 patches ; the color, as well as the form of the head and body, varying 

 much with age, food, and condition ; the black spots in the adult often 

 X-shaped or XX-shaped. Weight 15 to 40 pounds. North Atlantic, ascend- 

 ing all suitable rivers in northern Europe and the region north of Cape 

 Cod to Hudson Bay; formerly abundant in the Hudson and occasional in 

 the Delaware, its northern limit in the Churchill, Albany, and Moose 

 rivers, flowing into Hudson Bay; sometimes perfectly landlocked in 

 lakes in Maine and northward, where its habits and coloration (but no 

 tangible specific characters) change somewhat, when it becomes (in 

 America) vars. sehago and ouananiche. Similar landlocked varieties occur 

 in Europe. One of the best known and most valued of food-fishes, the 



