28 TELEOSTOMI. 



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

 with fulcra POLYODONTID^E, 20. 



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

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



ACIPENSEKID^E, 21. 



II. 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^E, 22. 



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



AMIID^, 23. 



EH. 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 body ; lower lobe of 



caudal longest; lower pharyngeals united. . EXOCCETID^E, 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^E, 36. 

 MM. Vent behind ventrals ; eyes normal. 

 N. Head more or less seal} 7 . 



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

 posteriorly. 



P. Teeth cardiform, unequal ESOCID^E, 89. 



PP. Teeth villiform, equal UMBRID^E. 38. 



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



laries alone CYPRINODONTID^E, 37. 



NN. Head without scales. 



Q. Gill membranes united with the isthmus ; lower pharyngeals 



falciform ; mouth toothless ; anterior vertebras coalesced. 

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

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



with less than 10 rays CYPRINHWK, 20. 



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



ten or more CATOSTOMID^E, 25. 



QQ. Gill membranes free from the isthmus; lower pharyngeals 



flattish ; anterior vertebrae not modified. 

 S. Lateral line present. 



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



ELOPID^E, 29. 

 TT. Lower jaw without gular plate. 



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



HIODOJJTHXE, 27. 



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



ALBULHXE, 28. 

 S3. Lateral line wanting. 



V. Mouth very wide, the maxillary reaching much beyond 



eye; snout short STOLEPHORID^E, 31. 



VV. Mouth moderate, the maxillary scarcely extending 



beyond eye CLUPEID.E, 30. 



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

 with the small mouth at the end FISTULARIID^E; 44. 



