FISHES OF CHESAPEAKE BAY 37 
AA. Ventral fins present, attached to the thorax or throat, under, anterior to, or slightly 
behind base of pectorals. 
a. Gill openings moderate or large, situated anterior to pectoral fins; carpal bones normally 
developed; the pectoral fins without a “wrist.” 
b. Ventral fins always with I, 5 rays. 
c. Ventral fins separate and distinct, never united and never forming a part of a sucking 
disk. 
d. Suborbital without a bony stay; cheeks not mailed; pectoral fins entire, without 
detached rays. 
e. Anterior dorsal fin converted into a sucking apparatus, forming a disk at nape, 
consisting of several crosswise partitions and a single lengthwise septum 
Echeneididse (remoras), p. 328 
ee. Anterior dorsal fin normal, not converted into a sucking disk. 
/. Dorsal and anal fins followed by a series of detached finlets; anal fin not 
preceded by free spines; caudal fin broadly forked 
Scombridx (mackerels), p. 200 
//. Dorsal and anal fins not followed by several detached finlets. 
g. Body elongate, spindle-shaped; head strongly depressed; snout broad; first 
dorsal with eight or nine free spines. .Rachycentridx (crab eaters), p. 234 
gg. Body not spindle-shaped; head never greatly depressed; snout not expanded. 
h. Anal fin preceded by two free spines (sometimes obsolete in very old, 
joined by membrane in very young); ventral fins present at all ages; 
oesophagus without teeth. 
i. Preopercle entire; caudal peduncle slender, frequently with lateral bony 
scutes; teeth, if present, small to moderate 
Carangidx (crevallies, pompanos, etc.), p. 216 
it. Preopercle serrate; caudal peduncle rather stout, never with bony 
scutes; teeth unequal, some of them enlarged 
Pomatomidx (bluefishes), p. 231 
hh. Anal fin not preceded by free spines. 
j. Oesophagus provided with lateral sacs containing teeth; anal fin long, 
similar to dorsal; ventral fins normal in young, sometimes reduced 
or wanting in adults Stromateid.se (butterfishes) , p. 210 
jj. Oesophagus not provided with teeth. 
k. Lateral line extending to end of caudal fin; anal fin with one or 
two spines. 
I. Backbone typically with 10+14 vertebrae 
Scixnidx (croakers and drums), p. 271 
II. Backbone typically with 14+10 vertebrae 
Otolithidse (weakfishes), p. 296 
kk. Lateral line ending at base of caudal. 
m. Nape with a fleshy flap resembling an adipose fin; similar but 
smaller fleshy flaps on sides of lower jaw near angle of mouth; 
dorsal fin continuous Branchiostegidse (tilefishes) , p. 305 
mm. No fleshy flap at nape or on lower jaw. 
n. Gills 4, a slit behind the fourth. 
o. Premaxillaries excessively protractile, their basal proc- 
esses very long, entering a groove at top of cranium 
just underneath the skin; scales large; fin spines strong; 
color silvery Gerridse (moj arras), p. 369 
oo. Premaxillaries only moderately protractile, or not pro- 
tractile. 
p. Anal fin with one or two spines; dorsal fins separate, 
with about 8 to 16 spines; form elongate; fresh-water 
fishes. 
