80 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
D. Dorsal and anal fins followed By finlets. 
E. Free anal sifines 2 Caraxgid.e, 75. 
EE. Free anal spines none Scojirrid^, 74. 
DD. Dorsal and anal witliout finlets. 
F. Upper jaw prolonged into a “sword” Xipiiiid^, 72. 
FF. Upper jaw not prolonged into a sword. 
G. Snborbital witb a bony stay Cottid.e, 107. 
GG. Snborbital witliont bony stay. 
II. Anal fin absent; candal fin rndimentary or directed upward. 
Traciiypterid.®, 100. 
HH. Anal fin present ; candal developed. 
I. Ventral rays less tban I, 5. 
J. Dorsal spines none at all ; lateral line witb prickles. 
ICOSTEIDiE, 101. 
JJ. Dorsal spines very few (less tban 6) BATRACiiiDyE, 114. 
JJJ. Dorsal spines unmerons Bleyniid.^, 112. 
II. Ventrals thoracic, I, 5, or more. 
K. Dorsal witb a series of bony plates at base Zexid.e, 81. 
KK. Dorsal witbont bony plates at base. 
L. Anal preceded by 2 free spines Car.\xgid.e, 75. 
LL. Anal witbont free Sicilies Traciiixid^, 102. 
BB. Gill -oiienings small, behind the pectoral fins, which are more or less j)edic- 
nlate. 
M. Gill-openings in or behind nj^x^er axil of pectorals; 
month small Maltheid/E, 126. 
MM. 'Gill-openings in or behind lower axil ; month large. 
N. Head comx)ressed ; no xisendobranchiae. 
Axtexxariidjj, 125. 
NN. Head dex^ressed ; psendobranchiaj xwesent. 
Lopiiiid^, 124. 
III.— VENTRAL FINS ENTIRELY WANTING. 
A. Gill-oxienings ventral, confluent in a longitudinal slit ; body eel-shaxied. 
Synapiiobraxchidje, 54. 
B. Gill-ox>euings lateral, or not conflaent. 
C. Gill membranes united to the isthmus (i. e., gill-ox>eniugs separated by an 
isthmus). 
D. Dorsal fin single, of sx)ines only. 
E. IMolar teeth xwesent Axarrhichadip.®, 113. 
EE. Molar teeth none Blexxiid^, 112. 
DD. Dorsal fins two, anterior sxnuous, x)osterior soft ; teeth incisor-like. 
Balistid^, 128. 
DDD. Dorsal fin undivided, the spines feeble or none. 
E. Snout tubular, bearing the short, toothless month at its end ; body mailed. 
F. Candal fin x>resent ; head in the line of the axis of the body. 
Syxgna^iiid^, 58. 
FF. Candal fin wanting ; head not in line of axis of body. 
H1PPOCAMPID.E, 59. 
EE. Snout not tubular. 
G. Body elongate, eel-shaped. 
H. Pectoral fins wanting. 
I. Gill-openings very small MuRiEXiD.E, 52. 
II. Gill-openings moderate Axguillid.e, 53. 
HH. Pectoral fins x)resent. 
