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 bonj' shields; 

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



ACIPENSEEID^, 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. 



AMIIDJ3, 23. 



HB. 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. . AMBLTOPSiDiE, 36. 

 MM. Vent behind ventrals; ej'es normal. 

 N. Head more or less scaly. 



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

 posteriorly. 



P. Teeth cardiform, unequal EsociD^, 89. 



PP. Teeth viliiform, equal Umbexd^ 38. 



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



laries alone CypeikodontiDjE, 37. 



NN. Head without scales. 



G. Gill membranes united with the isthmus ; lower pharyngeals 

 falciform ; mouth toothless ; anterior vertebrae coalesced. 

 a. 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 Cypeisid.e, 26. 



i2i2. 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 vertebrse not modified. 

 S. Laieral line present. 



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



ElopiDjE, 29. 

 TT. Lower jaw without gular plate. 



JJ. Tongue with canine teeth ; mouth tenninal, oblique. 



H10DOSTID.E, 27. 

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



Albulid^ 28. 

 B8. Lateral line wanting. 



V. Mouth very wide, the maxillary reaching much beyond 



eye; snout short Stolephokid^, 31. 



YV. Mouth moderate, the maxillarj' scarcely extending 



beyond eye Clupeid^e, 30. 



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

 with the small mouth aWhe end FisTnLAKiiD^ 44.' 



