164 



found to come under Prof. Agassiz's genus Percopsis. 

 Esox nobilior has been described by Richardson, and sup- 

 posed by him to be identical with E. lucius, of Europe. 

 It is in reahty a distinct species. 



Mr. Ayres said, on examination of the drawing of the 

 fish called Salmoperca, that it evidently belonged to the 

 genus Percopsis. 



PERCOPSIS PELLUCIDA. 



Description. General color, light brownish yellow, with lon- 

 gitudinal rows of brown spots, about 0.1 in. in diameter, usually 

 one along the dorsal line, and two rows on each side between 

 the dorsal and lateral line. A broad satin stripe embracing the 

 lateral line. Belly, white. Fins and flesh, translucent, the ver- 

 tebral column, the abdomen, and portions of the head only ap- 

 pearing opaque when held to the light. 



Fins all large in proportion to the size of the fish. The rays 

 of the pectoral reach half their length beyond the base of the 

 ventrals. Attachment of the ventrals beneath and a little ante- 

 rior to the beginning of the first dorsal, their points reaching 

 the anus. The anal fin has its first ray short and spinous. Cau- 

 dal fin, forked. 



Nostrils and eyes large ; irides yellow. Depression between 

 the eyes divided longitudinally by a bony ridge. Seven small 

 sinuses along the under jaw on each side. Edge of the pre- 

 operculum finely serrated. Scales rough nn account of their 

 serrated margins. Length, from 3 to 5 inches. The following 

 are measurements from one of three nearly equal recent speci- 

 mens, which were before me when the above description was 

 made. Total length, 3.9 in. ; to the centre of the eye, .5 ; 

 posterior edge of the operculum, .9 ; pectoral fin, 1 ; ventral, 

 1.45; first dorsal, 1.5; and 2.1; adipose, 2.6; centre of 

 the base of caudal, 3.2 ; longest caudal rays, .7; central, half 

 as long. 



Rays B. 6, D. - 11 —0, P. 13, V. 8, A. |, C. Hf. 



This fish was first described by me in 1841, from a single spe- 

 cimen found dead on the shore of Lake Champlain, and received 

 the name here given to it in my manuscript notes. In 1847, 

 two other specimens were found dead on the shore. The 



