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. 
b. (Clupeoidea.) No adipose fin. 
c. Gular plate present between rami of mandible. ELOPIDA 
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. DOROSOM ATID A 
ddd. Mouth subinferior, very large, below a tapering pig-like 
snout; maxillary very long. ENGRAULIDID® 
bb. (Salmonoidea.) ' Adipose fin well developed. 
e. Stomach siphonal, not having form or blind sac; pyloric 
coeca many. SALMONIDA 
ee. Stomach ccecal, of form of blind sac; pyloric coeca gen- 
erally many. ARGENTINIDA® 
aa. (Iniomi.) Mesocoracoid arch wanting or atrophied. SYNODONTIDA 
Family ELOPIDZ. 
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 villiform teeth in both jaws, on vomer, 
palatines, pterygoids, tongue and base of skull. No large teeth. 
Opercular bones thin, with expanded membranaceous borders. 
