TKOUT PERCH. 899 



sprinkled, living arrow of the White Water; able to zigzag up the cata- 

 ract ; able to loiter in the rapids, whose dainty meat is the glancing 

 butterfly." 



FAMILY XIV. PERCOPSID^. THE TROUT 



PERCHES. 



Body modeiately elongate, Bomawhat compiesBed, the candal pednncle long and slen- 

 der ; head conical, pointed, naked ; month small, horizontal ; maxillary short, narrow, 

 ■withont supplemental bone, not reaching to the large eye ; margin of upper jiw formed 

 by premaxillaries alone, Trhich are short and not protractile ; teeth very small, vUliform 

 on premaxillaries and lower jaw only; tongne short, adherent; gill-membranes sepa- 

 rate, free from the isthmus ; paeudobrancbise present ; branchiostegals six ; gill-rakers 

 short, tnberole-llke ; operole with entire edges; lower limb of the preopercle well de- 

 veloped, the angle nearly a right angle, its inner edge with a raised crest ; bones of the 

 head cavernous, as in Aeerina and Ericymha ; cranium with a raised crest, which dees 

 not extend to the occiput ; scales moderate, rather thin, adherent, their edges strongly 

 ctenoid; lateral line continuous ; dorsal short, median; ventrals anterior, jast in front 

 of the dorsal, 8-rayed ; pectorals narrow, placed rather higher than usual ; anal small ; 

 candal forked ; adipose fin present, small; stomach siphonal, with about 10 well devel- 

 oped pyloric coeca; ova rather large, not falling into the abdominal cavity before exclu- 

 sion ; air-bladder present ; small fishes of the fresh waters of the cooler parts of Amer- 

 ica ; a single genus, with probably but one species. The group is one of special interest, 

 as it combines with ordinary salmonoid characters the structure of the head and month 

 of apereoid, resembling notably the European genus Aeerina. 



Gentts 54. FEBCOPSIS. Agassiz. 



Percopsis, Agasbiz, Lake Superior, 1850, 284. 

 Salmoperca, Thompsost, 1853. 



Type, Percopsis guttatus, Agassiz. 



Etymology, perhe, perch ; opsis, appearance. 



The characters of the genns are iaclnded above. 



, 103. Pbrcopsis guttatus Agassiz. 



Trout Percli. 



Percopsis guttatus, Agassiz, Lake Superior, 1850, 386.— Gunther, Cat. Fish. Brit. Mus., 



vl, 207.— JOKDAN, Man. Veit. 2d Ed., 1878, 270, 

 Salmoperca pelhtcida, Thompson. 



Pale olivaceous, a silvery stripe along the lateral line, becoming obsolete forwards ; 

 upper parts with obscure, ronnd dusky spots made of dark points. Head slender and 

 conical; month small, subinferior, maxillary not nearly reaching front of orbit; caudal 

 pednncle long and slender ; peritoneum silvery ; head 3 4-5 in length ; depth about 

 4}; D. 11 ; A. 8 ; Lat. 1. 50. Length abont 6 inches. 



Habitat, Great Lake Kegion, extending southward to the Dalaware, Ohio and Kansas 

 Blvers ; abundant only in tributaries of the Great Lakes. 



