KEY TO FAMILIES OF PISCES. 75 



** * Dorsal fins 2, the anterior of spines only, the posterior chiefly of soft rays. 



M. Pectoral fin with 5 to 8 lowermost rays detached and' fila- 

 mentous POLYNEMID^E, 68. 



MM. Pectoral fin entire. 



N. Snout tubular, bearing the short jaws at the end; body 



compressed CENTRISCIDJE, 60. 



NN. Snout not tubular. 



O. Teeth strong, unequal; lateral line present. 



SPHYRJSNIDJE, 67. 



OO. Teeth small or wanting; lateral line obsolete. 

 P. Dorsal spines 4, stout ; anal spines 3. .MUGILID^E, 65. 

 PP. Dorsal spines 4 to 8, slender ; anal spine single. 



ATHERINID.E, 66. 

 **** Dorsal fin soft-rayed, followed by a series of detached fiulets. 



SCOMBERESOCID^E, 57. 



*** j) orsa i fin single, of soft rays only or with a single spine. 

 a. Tail evidently heterocercal. 



b. Body naked; snout with a spatulate blade; mouth wide, without barbels. 



POLYODONTID^E, '25. 



Z>Z>. Body with 5 series of body shields ; mouth inferior, toothless, preceded by 4 



barbels ACIPENSERIDJE, -J i. 



66Z>. Body scaly, 

 c. Scales cycloid ; a broad bony gular plate; dorsal fin many-rayed. 



AMIIDJE, 28. 



cc. Scales ganoid ; no gular plate ; dorsal fin short LEPIDOSTEID^E, 27. 



aa. Tail not evidently heterocercal. 

 d. Body naked. 

 e. Throat with a long barbel ; no caudal filament ; mouth large. 



STOMIATIDJE, 45. 



ee. Throat without barbel ; caudal fin with a long filament ; mouth small. 



FISTULARIID.E, 61. 

 eee. Throat without barbel ; no caudal filament; gill membranes joined to 



the isthmus C YPKINID^E, 31. 



dd. Body scaly. 



/. Pectoral fins inserted near the axis of the body ; lower pharyugeal 



bones fully united ; lateral line along the 

 sides of the belly.. .SCOMBERESOCID.E, 57. 



ff. Pectoral fins inserted below the axis of the body ; lower pharyngeals 



separate. 



g. Vent in front of ventral fins; eyes concealed AMBLYOPSHXE, 43. 



gg. Vent behind ventral fins ; eyes normal. 

 //. Head scaly, more or less. 



i. Upper jaw not protractile, its lateral margin formed by the 



maxillaries. 



j. Teeth cardiform ; jaws depressed, prolonged ESOCHXE, 51. 



jj. Teeth villiform ; jaws short UMBRID/E, 50. 



ii. Upper jaw protractile, its margin formed by prernaxillaries 



alone C YPRINODONTID^E, 49. 



hh. Head naked. 



Jc. Gill-opening separated by an isthmus; mouth toothless; 

 lower pharyngeals falciform. 



I. Dorsal fin with a serrated spine CYPRINID^E, 31. 



II. Dorsal fin without serrated spine. 



m. Dorsal fin with (usually) less than 10 (developed) rays; 

 pharyugeal teeth few (less than 8). 



CYPRINID2E, 31. 



