Jordan and Evermann. Fishes of North America. 2877 



M. Head with a large divided luminous plate in place of eyes. 



LXXII, IPNOPID^E, 546. 



MM. Head with eyes concealed beneath the skin ; vent at the throat. 



XCIII, AMBLYOPSID.E, 702. 

 MMM. Head with normally developed eyes. 



N. Body with a coat of mail; maxillary with barbels. 



XXXV, LORICARIID.E, 155. 

 NN. Body with ordinary scales. 

 O. Anal fin with many spines; mouth toothless, sucker-like. 



LXXXVI1I, LIPOGENYID^E, 619. 

 OO. Anal fin without distinct spines. 

 P. Pectoral fins inserted high, near axis of body ; lower pharyn- 



geals united; lateral line. along sides of belly. 

 Q. Jaws each with long sharp teeth mixed with smaller ones. 



XCIV, ESOCID.E, 708. 



QQ. Jaws with small equal teeth, conic or tricuspid. 

 E. Lower jaw more or less produced; teeth tricuspid. 



XCV, HKMIRAMPHID^E, 718. 

 ER. Lower jaw a little produced; teeth conic; pectorals elongate, 



forming an organ of flight XCVII, EXOCCETID.E, 726. 



PP. Pectoral fins inserted below axis of body; lower pharyngeals 

 separate. 



5. Gill membranes broadly joined to the isthmus; head naked; no 



teeth in jaws. 

 T. Lower pharyngeal teeth very numerous, in 1 row like the teeth 



of a comb. (Suckers.) XXXVI, CATOSTOMID^E, 161. 



TT. Lower pharyngeal teeth few, fewer than 8, in 1 to 3 rows. (Carp ; 



Chubs ; Minnows. ) XXXVII, C YPRINID.E, 199. 



SS. Gill membranes free from the isthmus. 

 V. Throat with a long barbel; sides with phosphorescent spots. 



LXXIX, STOMIATID^E, 587. 

 UU. Throat without barbels. 

 V. Phosphorescent snots present ; teeth unequal. 



LXXVII, CHAULIODONTID^E, 578. 

 VV. Phosphorescent spots none. 

 W. Head scaly, more or less. 

 X. Maxillaries connate with premaxillaries ; jaws long. 



LXVII, SYNODONTID.E, 532. 

 XX. Maxillaries distinct. 

 Y. Upper jaw not protractile, its lateral margins formed by the 



maxillaries; lateral line more or less developed. 

 Z. Teeth cardiform; jaws depressed, prolonged. XCI, LUCIID^E, 624. 

 ZZ. Teeth villiform; jaws short; no lateral line. 

 a. Pectoral very broad, of about 35 rays. . LXXXIX, DALLIID^E, 620. 



aa. Pectoral narrow, of about 13 rays XC, UMBRID.E, 622. 



YT. Upper jaw protractile, its margin formed by premaxillaries 



alone; no lateral line XCII, PCECILIHXE, 630. 



WW. Head naked. 



a. Anterior vertebras coalesced and modified; no pseudobranchise ; 

 jaws with strong canines.. XXXVIII, ERYTHRINID.E, 330. 

 aa. Anterior vertebras normal, not modified. 



6. Dorsal fin inserted more or less before anal (rarely slightly 



behind it); shore fishes or river fishes, usually silvery 

 in coloration and with skeleton firm; air bladder well 

 developed. 



c. Gular plate present, between branches of lower jaw; mouth 



large; teeth present, all pointed; axillary scales and 



sheaths large LVI, ELOPID^E, 408. 



cc. Gular plate none. 



d. Lateral line well developed. 



e. Teeth present, no accessory branchial organ. 



