Artificial Key to the Families of American Food and Game Fishes 



FF. Body uniformly covered with cycloid scales; dorsal spines mostly very 



high and filamentous XXXVII, Nematistiid^, 294 



BB. Ventral fins with or without spine, the number of soft rays fewer than 5. 

 G. Upper jaw not prolonged into a sword. 

 H. Dorsal fin with some spines or simple rays. . . . XXXIII, Lepidopid^, 289 



HH. Dorsal fins of soft rays only LXXIV, Gadid^, 508 



GG. Upper jaw prolonged into a bony sword; dorsal fin long and high; size 

 large XXXV, IstiophoridjE, 291 



IV —VENTRAL FINS WHOLLY WANTING 



A. Premaxillary and maxillary wanting or grown fast to the palatines; body 



greatly elongate, eel-shaped; gill-openings restricted to the sides; 

 scales minute or wanting; scapular arch not attached to the skull. 

 Eels, 



B. Gill-openings well-developed; tongue present. 



C . Skin covered with rudimentary embedded scales, usually linear in form, 



arranged in small groups, and placed obliquely at right angles to 

 those of the neighbouring groups; pectorals and vertical fins well 

 developed, the latter confluent about the tail; lateral line present; 

 posterior nostril in front of eyes; tongue with its margins free. 



VI, Anguillid^, 76 

 CC. Scales wholly wanting; eggs (so far as known) of moderate size, much 



as in ordinary fishes VII, Leptocephalid^, 81 



BB. Gill-openings small; no tongue VIII, Mur^nid^. 82 



A A. Premaxillary and maxillary present, often immovably united to rest 

 of cranium. 



B. Gill-membranes broadly united to the isthmus, restricting the gill-open- 



ings to the sides. 



C. Teeth in each jaw confluent into one LXVI, M0LID.B, 492 



CC. Teeth separate; body enveloped in a bony box..LXIV, Ostracud^, 489 

 BB. Gill-membranes free from the isthmus. 



E. Caudal fin wanting; body naked, greatly elongate. 



XXXIV, Trichiuridvs:, 290 

 EE. Caudal fin present. 



F. Upper jaw prolonged into a sword; size very large 



XXXVI, XiPHiiD^, 293 

 FF . Upper jaw not prolonged into a sword. 



G. Belly with a series of bony scutes along its edge; body much compressed. 



XIII, Clupeid^, 95 

 GG. Belly not armed with scutes. 



H. Body ovate, much compressed XLIV, Stromateid/e, 328 



HH. Body oblong or elongate, much longer than deep. 



XXIX, Ammodytid^, 263 



545 



