KEY TO FAMILIES OF PISCES. 
75 
* Dorsal fins 2, tlie auterior of siiiues only, tlie i)osterior chiefly of soft rays. 
M. Pectoral flu with 5 to 8 lowermost rays detached and fila- 
mentons POLYXEMiDiE, 68. 
MM. Pectoral tin entire. 
N. Snout tubular, bearing the short jaws at the end ; body 
compressed Cextriscidjl, 60. 
KX. Snout not tubular. 
O. Teeth strong, unequal; lateral line present. 
Sphye^xid.®, 67. 
00. Teeth small or wanting; lateral line obsolete. 
P. Dorsal spines 4, stout ; anal siiines 3 . . Mugilid.e, 65. 
PP. Dorsal spines 4 to 8, slender ; anal si)ine single. 
ATHERIXID.E, 66. 
* * Dorsal flu soft-rayed, followed by a series of detached fiulets. 
SCOMBEP.ESOCID^, 57. 
Dorsal fin single, of soft rays only or with a single spine. 
a. Tail evidently heterocercal. 
b. Body nahed ; snout with a si^atulate blade ; mouth wide, without barbels. 
POLYODOXTIDiE, 25. 
bb. Body with 5 series of body shields ; mouth inferior, toothless, preceded by 4 
barbels..: Acipexserid^, 23. 
bbb. Body scaly. 
c. Scales cycloid ; a broad bony gular plate ; dorsal fin many-rayed. 
AMIID.E, 28. 
cc. Scales ganoid; no gular iflate; 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. 
STOMIATID.E, 45. 
ee. Throat without barbel ; caudal fin with a long filament ; mouth small. 
Fistulariid^, 61. 
eee. Throat without barbel; no caudal filament; gill membranes joined to 
the isthmus CYPRiXLDiE, 31. 
dd. Body scaly. 
/. Pectoral fins inserted near the axis of the body; lower pharyngeal 
bones fully united ; lateral line along the 
sides of the belly.. .Scojiberesocid.e, 57. 
//. Pectoral fins inserted below the axis of the body ; lower pharyngeals 
separate. 
ff. Vent in front of ventral fins; eyes concealed Aaiblyopsid.e, 48. 
ffff. Vent behind ventral fins; eyes normal. 
h. Head scaly, more or less. 
i. Upper jaw not protractile, its lateral margin formed by the 
maxillaries. 
J. Teeth cardiform ; jaws depressed, prolonged Esocid.e, 51. 
jj. Teeth villiform ; jaws short Umbeid^, 50. 
ii. Upper jaw protractile, its margin formed by premaxillaries 
alone Cypeixodoxtid.e, 49. 
hli. Head naked. 
k. Gill-opening separated by an isthmus; mouth toothless; 
lower pharyngeals falciform. 
7. Dorsal fin with a serrated spine Cypeix’id^, 31. 
77. Dorsal fin without serrated spine, 
m. Dorsal fin with (usually) less than 10 (developed) rays; 
pharyngeal teeth few (less than 8). 
Cyprlxid^, 31. 
