90 REPORT OF NEW JERSEY STATE MUSEUM. 



Order ISOSPONDYLI. 



The Isospondylous Fishes. 



A large group typified by the herring and trout, and com- 

 prising most of the marine soft-rayed fishes, some inhabiting the 

 oceanic abysses, apparently degenerating. 



Key to the sub-orders and families. 



a. Mesocoracoid well developed. 



h. (Chipeoidea.) No adipose fin. 

 . c. Gular plate present between rami of mandible. elopid.?; 



cc. No gular plate. 



d. Mouth terminal ; maxillary of about 3 pieces ; stomach not 



gizzard-like. clupeid.^ 



dd. Mouth small, inferior ; maxillary simple or nearly so ; 



stomach gizzard-like. dorosomatid.^ 



ddd. Mouth subinferior, very large, below a tapering pig-like 



snout; maxillary very long. engraueidid.e 



bb. (Salmonoidea.) Adipose fin well developed. 



e. Stomach siphonal, not having form or blind sac ; pyloric 

 coeca many. salmonid.i; 



ee. Stomach coecal, of form of blind sac; pyloric cceca gen- 

 erally many. argentinid.s; 

 aa. (Iniomi.) Mesocoracoid arch wanting or atrophied. synodoxtid,^ 



Family ELOPID^. 



The Tarpons. 



Body elongate, more or less compressed. Eye large, with adi- 

 pose eyelid. Premaxillaries not protractile, short. Maxillaries 

 forming lateral margins of upper jaw, composed of about 3 

 pieces extending backward beyond eye. An elongate bony plate 

 between branches of lower jaw. Mouth broad, terminal, lower 

 jaw prominent. Bands of viUiform teeth in both jaws, on vomer, 

 palatines, pter3^goids, tongue and base of skull. No large teeth. 

 Opercular bones thin, with expanded membranaceous borders. 



