28 TELEOSTOMI. 



J. Body naked; snout spatulate; mouth wide, without barbels ; caudal 



with fulcra Polyodontid^, 20. 



J J. Body with 5 series of bony shields; head with bony shields; 

 mouth inferior, toothless, preceded by 4 barbels ; fins with fulcra. 



ACIPENSEKID^, 21. 

 //. Caudal rounded or lanceolate; head with a bony casque. 

 X. Scales ganoid (rhombic, enamelled plates) ; no gular plate ; fins with 



fulcra; dorsal fin short Lepisosteid^, 22. 



XX. Scales cycloid ; a bony gular plate ; no fulcra ; dorsal long. 



AmiidjE, 23. 

 Hn. Tail not evidently heterocercal (except in the very young). 

 Y. Scales cycloid. 

 K. Side of belly with a conspicuous ridge or lateral line ; pectoral fins 

 inserted high, on or above the axis of the bodj* ; lower lobe of 

 caudal longest; lower pharyngeals united. . Exoccetid^, 42. 

 KK. Edge of belly without conspicuous ridge or lateral line; pectoral 

 fins inserted usually below axis of body ; lower pharyngeals 

 separate. 

 M. Vent before ventrals ; eyes rudimentary. . Amblyopsid^, 36. 

 MM. Vent behind ventrals ; e3'es normal. 

 .A^. Head more or less scaly. 



0. Upper jaw not protractile, its margin formed by maxillaries 

 posteriorly. 



P. Teeth cardiform, unequal Esocid^, 89. 



PP. Teeth villiform, equal TJmbeidjE, 38. 



00. Upper jaw very protractile, its edge formed by premaxil- 



laries alone Cypeinodontid^, 37. 



NN. Head without scales. 



Q. Gill membranes united with the isthmus; lower pharyngeals 

 falciform; mouth toothless ; anterior vertebrae coalesced. 

 R. Pharyngeal teeth larger, in one or more rows, the main 

 row with less than 8 teeth; dorsal (in native species) 



with less than 10 rays Cypeinid^, 26. 



RR. Pharyngeal teeth very numerous, in one row; dorsal rays 



ten or more Catostomid^, 25. 



QQ. Gill membranes free from the isthmus; lower pharyngeals 

 flattish ; anterior vertebra; not modified. 

 S. Lateral line present. 



T. Lower jaw with a gular plate ; fins with scaly sheaths. 



Elopid^, 29. 

 TT. Lower jaw without gular plate. 



U. Tongue with canine teeth; mouth terminal, oblique. 



HlODOHTID^, 27. 



UU. Tongue with blunt teeth; mouth inferior, horizontal. 



Albulid^, 28. 

 88. Lateral line wanting. 



V. Mouth very wide, the maxillary reaching much beyond 



eye; snout short. . . . Stolephokid^, 31. 



VV. Mouth moderate, the maxillary scarcely extending 



beyond eye Clupeid^, 30. 



TT. Scales none; caudal with a long filament; snout long, tubular, 

 with the small mouth at the end. . . FisTnLARiiDjEi 44. 



