28 TELEOSTOMI. 



J". 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. 



ACIPENSERID.E, 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. 



AMIID^E, 23. 



HE. 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. . AMBLYOPSIDJE, 36. 

 MM. Vent behind ventrals ; eyes normal. 

 N. Head more or less scaly. 



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

 posteriorly. 



P. Teeth cardiform, unequal ESOCID^E, 39. 



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



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



laries alone CYPRINODONTIDJE, 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 CATOSTOMIDJS, 25. 



QQ. Gill membranes free from the isthmus; lower pharyngeals 



flattish ; anterior vertebrae not modified. 

 S. Lajteral 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. 



HlODONTID^E, 27. 



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



ALBULID^E, 28. 

 SS. Lateral line wanting. 



F. 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. 



