ZOOLOGY. 



THE SOCIAL-DORADO, OR BLUE-FISH. 



(Coryphcena Socialis, N. Sp.) 



This is a new species of a fish commonly called the 

 Dolphin. Its average length does not exceed one foot 

 and a half. Rays of the pectoral fin, 20. Dorsal, 53. 

 Anal, 24. 



Its colour, when in the water, is deep-blue, with 

 circular black spots. When removed from the sea, it 

 assumes a yellow-green or olive tint, changing to a 

 dull-silver or lead- colour ; which last remains permanent 

 after death, as also do the circular spots on the body. 



Large shoals of this species came about us in lat. 

 27 N., Pacific Ocean, and on the Equator, in long. 

 166 W. They accompanied the ship for several suc- 

 cessive days, swimming astern or on the quarter, and 

 many were taken by hook and line. Notwithstanding 

 their small and apparently youthful size, several of these 

 fish had large impregnated roes, which went far to 

 prove that they were adult specimens. They chiefly 

 differ from the common Dorado (Coryhcena hippuris) in 

 the increased number of rays in their dorsal fin in 

 their diminutive size and in the circumstance of their 

 associating together in large shoals. 



THE PILOT-FISH. 



(Gasterosteus Ductor, Linn.) 



The average length of this fish is about six inches ; 

 though we took one example, in the Pacific, which 

 measured one foot two inches. The body is somewhat 

 cylindrical, and neatly formed. The colour of the head 

 and back is steel-blue ; abdomen silvery ; sides marked 

 with five broad black bands ; fins mottled black and 

 white, and mostly tipped with white; inner circle of 



