320 
BULLETIN OF THE UNITED STATES FISH COMMISSION, 
HIPPOGLOSSIELffi. Halibut Tribe. 
Large-mouthed flounders with the ventral fins symmetrical. — Mouth symmetrical, the jaws and denti- 
tion nearly equally developed on both sides; gape usually wide, maxillary more than one-third length 
of head. Lower pharyngeals narrow, usually with but 1 or 2 rows of sharp teeth; teeth in jaws usually 
acute. Eyes large; edge of preopercle free. Pectoral and ventral fins well developed, the ventral fins 
similar in position and in form of base, that of eyed side not being attached along ridge of abdomen. 
Septum of gill-cavity without foramen. 
The only genera of Hipp oglossin x having species ranging as far south on our Atlantic coast as 
Florida are Paralichthys, Ancylopsetta, Notosema, and Gastropsetta. Though no species of this group is 
known from Porto Rico, we give a key to these 4 genera, as some or all of them may be hereafter found 
in Porto Rican waters. 
a. Dorsal fin beginning in advance of eye; teeth sharp, uniserial or smooth. 
b. Scales weakly ciliated; caudal fin with a distinct peduncle; mouth large; teeth unequal, some of anterior canine-like; 
gillrakers rather long and slender; no dorsal lobe nor produced ventral rays; vertebrae 35 to 41 Paralichthys 
bb. Scales very strongly ctenoid on both sides of body; mouth smallish, with small, sharp teeth; anterior rays of dorsal 
more or less exserted, thus forming a more or less distinct lobe; gill-membranes considerably united; gillrakers 
short and broad; caudal peduncle short; left ventral produced; vertebra (in A. quadrocellata ) 9 + 26 = 35. Lateral 
line with its tubes simple, not branched. 
c. Body broad, ovate, depth more than half length; dorsal lobe and left ventral moderately produced Ancylopsetta 
cc. Body elliptical, depth not more than one-half length; dorsal lobe and left ventral greatly produced Notosema 
bbb. Scales entirely smooth; caudal peduncle short; mouth small; gillrakers short and thick; dorsal with an anterior lobe; 
left ventral elongate Gastropsetta 
PSETTIN2E. Turbot Tribe. 
Large-mouthed flounders, with ventral fins unsymmelrical . — Mouth symmetrical, the dentition nearly 
equally developed on both sides; gape usually wide (narrow in Plcitophrys, Etropus, etc. ), maxillary com- 
monly more than one-third length of head; lower pharyngeals narrow, each with one or more rows or a 
narrow band of small, sharp teeth; teeth in jaws acute; eyes not minute; pectorals and ventrals usually 
well developed; edge of preopercle free; ventral fins dissimilar in form or in position, that of left or eyed 
side inserted on ridge of abdomen, its base extended along this ridge, its rays more or less wide apart; 
caudal fin rounded or subtruncate; no accessory lateral line; anal spine usually weak or obsolete; a 
pelvic spine sometimes developed; vertebrse in moderate or small number, 31 to 45. Body sinistral. 
Species chiefly tropical or subtropical in distribution. Of the 10 recognized American genera of 
this subfamily, 4 have Porto Rican representatives, in fact, all the species of flounders thus far known 
from Porto Rico belong in this group. 
a. Pectoral fin present on each side; septum of gill-cavity below gill-arches without foramen; a deep emargination 
near isthmus; ventral fins free from anal. 
5. Vomer with teeth; lateral line with a strong arch in front; teeth subequal, in villiform bands; body broadly ovate; 
caudal fin subsessile; interorbital area broad; scales small, cycloid; gillrakers long and slender; anterior dorsal 
rays produced; vertebra 36 Lothopsetta 
bb. Vomer toothless; ventral fins free from anal; caudal fin subsessile. 
c. Lateral line with a distinct arch in front; teeth small, uniserial, or imperfectly biserial. 
d. Interorbital space more or less broad, deeply concave, at least in males; form broad-ovate; gillrakers short and 
thick. 
e. Scales small, ctenoid, adherent, 75 to 100 or more; anterior rays of dorsal not elevated; pectoral of left side usually 
filamentous in male; vertebra (in P. lunatus) 9 + 30 = 39 Platophrys, 155 
dd. Interorbital space a narrow ridge; dorsal not elevated in front. 
/. Gillrakers slender; right ventral elongate; scales ctenoid Trichopsetta 
cc. Lateral line without arch in front. 
g. Teeth in upper jaw biserial, in lower uniserial, front teeth of upper jaw enlarged; vertebrse 35 or 36; gillrakers 
short; interorbital space broad in male Syacium, 156 
gg. Teeth in each jaw uniserial; interorbital space very narrow, ridges coalescing between eyes. 
h. Mouth not very small, maxillary more than one-third length of head. 
i. Gillrakers very short and thick, tubercle-like. 
j. Scales cycloid, small, and firm Cyclopsetta 
ii. Gillrakers slender, of moderate length; scales thin, deciduous, ciliated; vertebra 34 to 40 Citharichthys, 157 
hh. Mouth very small, teeth subequal, maxillary less than one-third length of head; scales thin; teeth uniserial; 
vertebrae 9 + 25 = 34 Etropds, 158 
aa. Pectoral fin of blind side wanting; eyes very close together; caudal fin subsessile; teeth small, uniserial; mouth 
moderate; lateral line of eyed side arched, that of right side nearly straight; dorsal fin beginning on snout, its 
anterior rays not exserted, its rays all simple and very numerous; gillrakers few and feeble; scales small; 
body thin, very elongate; vertebra (in M. sessilicauda) 43; (deep-sea flounders) • Monolenb 
