814 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
similar, shorter; caudal various, sometimes coalesceut -with dorsal and 
anal; pectorals inserted rather high, sometimes wanting; ventrals 
under the pectorals, usually of several soft rays, sometimes wanting. 
Fishes mostly carnivorous, inhabiting sandy bottoms in all seas, some 
species ascending rivers. Many of them are important food-fishes. 
Genera about 40; species nearly 400. 
(Pleuronectidw Giintlier, iv, 399-504.) 
a. Pectoral and ventral fins botli present; caudal distinct; margin of preopercle more 
or less free. 
Mouth large; teeth nearly equally developed on both sides of the mouth, 
c. Ventral fin of the left side inserted nearly on the ridge of the abdomen; body 
sinistral. 
d. Vomer with teeth; lateral line arched in front; scales small or obsolete. 
Bothus, 449. 
dd. Vomer toothless; lateral line not arched; scales well developed, mostly 
ciliated Citharicuthys, 450. 
cc. Ventral fins both lateral; vomer and palatines toothless, 
e. Caudal fin lunate. 
/. Lateral line arched in front; scales cycloid Hippoglossus, 451. 
ff. Lateral line not arched. 
g. Teeth not arrow-shaped; gill-rakers few, short. 
Platysomatichthys, 452. 
gg. Teeth arrow-shaped; gill-rakers numerous, long. 
Atheresthes, 453. 
ee. Caudal fin not lunate, the middle rays produced. 
h. Lateral line arched in front; body usually sinistral. 
Paralichtiiys, 454. 
hh. Lateral line not arched ; body dextral. 
Hippoglossoides, 455. 
Mouth small; teeth, if present, most developed on the blind side. 
j. Teeth small, acute, in several series; lateral line nearly straight, 
with an accessory branch ; scales small, cycloid ; 
eyes dextral. 
k. Lips longitudinally plicate; dorsal fin beginning on the blind 
side Pleuroxichthys, 456. 
kk. Lips simple; dorsal fin beginning on the median lin<'. 
Hypsopsetta, 457. 
jj. Teeth in one series. 
I. Teeth rather large, bluntish or trenchant; eyes dextral (some- 
times sinistral in one species); ventrals (usually) both 
lateral. 
m. Dorsal fin with less than 80 rays; anal with less than GO. 
Pleuroxectes, 458. 
mni. Dorsal fin with more than 95 rays ; anal with more than 80 ; 
body unusually elongate. 
n. Left side of skull with strong mueous cavities; anal spine 
present Glyptocepiialus, 459. 
nn. Left side of skull without conspicuous mucous cavities; 
anal spine obsolete Cynicoglossus, 460. 
II. Teeth small, acute, in one series; lateral line nearly straight, 
simple; scales thin, ctenoid; eyes sinistral; left ven- 
tral on ridge of abdomen.... ;Etropus, 461. 
