450 ZOOLOGY. 



high degi'ee of elaboration and diversity in the bones of the 

 head. The skeleton is usually completely ossified. The 

 bones of the skull and of the jaws are fully developed. The 

 lower jaw is attached to the skull by a susjieusorium of sev- 

 eral well-marked bones, including a symplectic, while the 

 hyoid and gill arches are well developed, as is the scapular 

 arch. The brain has small olfactory lobes and a small cere- 

 bellum. The scales are generally present, and either cte- 

 noid {i.e., rough-edged) or cycloid {i.e., rounded but smooth 

 on the edge). The common examples are the carp, herring, 

 trout and salmon, pike, perch, cod, and flounder. 



Turning now to some 'of the more characteristic members 

 of the order, we first notice one of the lowest Teleosts, the 

 electrical eel {Gyiimotus electricus Linn.) of South Amer- 

 ica, which is two metres in length, and is characterized by 

 its gTeatly developed electrical Ijutteries. These are four in 

 ntimber, situated two on each side of the body, and together 

 form nearly the whole lower half of the trunk. The plates 

 of the cells are vertical instead of horizontal, as in the tor- 

 pedo, while the entire batteries or cells are horizontal, in- 

 stead of vertical, us in the electrical ray. The nerves sent 

 to the batteries of the eel are supplied by the ventral 

 branches of about two hundred pairs of spinal nerves. 



Succeeding these and allied forms are the herrings {Chi- 

 peidm), represented by the common English herring, Cliipea 

 liarengiis Linn., which inhabits both sides of the Xorth 

 Atlantic, extending on the American side from the polar 

 regions to Cape Cod; the alewife, Pomolohus pseudoharengus 

 Gill, which ranges from Xewfoundland to Fh rida ; the shad, 

 Ahsa ."iiiiidicxiiiia Storer, which has the same geographical 

 distribution as the alewife ; and the menhaden or jwov, 

 Brevoortia tyrannus (Joode, which extends from the coast 

 of ]\Iaine to Cape Hattera^. These, Avith the cod, hake, 

 haddock, salmon, and a few other species, comprise our 

 most valuable marine food-fishes. The fisheries of the 

 Tuited Siaies yield about >?4U, 000. 000 annually, whilst those 

 of Great Britain amount to about §40.000,000, and those of 

 Xorway about S10,000,000. 



Tlie herring is a deep-water fish which visits the coast in 



