117 



ALO^^A. 



This genus is disUngm'shed from Chipea by a recess in the middle 

 of the line in front of the middle jaw; and however slight the mark 

 by which they are sejiarated, it is convenient as pointing out a family 

 which differs in its habits from those of the genus Clupea, as i ow 

 defined. 



In almost all fishes in which the tail is forked, the upper and lower 

 divisions act in some measure as separate fins, their action being often 

 in opposite directions; but in the Cliipeoi, or Herring family, the separation 

 of the lobes is particularly conspicuous; and in the genus Alosa it is 

 still wider, the separation being marked with a difference of structure; 

 at which part there are two peculiar fan-shaped rays, which must have 

 a different function from those above and below. At this part the 

 body is only moderately covered with scales generally; which renders 

 the structure of our scale-tailed species the more remarkable. The air- 

 bladder is long and slender, and the tube which connects it with the 

 vent is even more slight than in the Herring. 



ALLIS SHAD. 



ALEWIFE. DAMIN HERRING. 



Shad, WiLLOUGiiBY ; Plate p. 3, f, 2, Agone, and p. 



227, but he confounds this species with 

 A. finta, the Twait Shad; as do many 

 others. 



Clupea alosa, Cuviek. Jenyns; Manual, p. 438. 



Alosa vulgaris, Yarkell; Br. Fishes, vol. ii, p. 213. 



This species is widely distributed in the moderately temperate 

 regions, and in the Mediterranean appears to have attracted 

 attention at an early date; as it is noticed, under the name of 

 Thrissa, generally by the writers on Natural History among 

 the Greeks and Romans. 



