THE FISHES OF PORTO RICO. 
329 
280. Etropus crossotus Jordan & Gilbert. 
Head 4. 8 in length; depth 1.75 to 2; I>. 76 to 85; A. 56 to 67; V. 6; scales 42 to 48; vertebrae 9 -(-25 = 34. 
Body oval and strongly compressed, with the dorsal and ventral curves nearly equal; both outlines 
strongly arched anteriorly, body much deeper in the adult; head very small; snout short; mouth 
very small, its cleft not so long as diameter of orbit; teeth conical, pointed, close-set, strongly incurved, 
in a single series, those in upper jaw on the blind side only, those on lower jaw on both sides; eyes 
large, lower in advance of upper, separated by a very narrow scaleless ridge, which extends backward 
above the preopercle; edge of opercle on blind side with a row of conspicuous white cilia; upper 
nostril turned somewhat to blind side; anterior nostril on left side, with a very slender chrus; dorsal 
fin commencing over front of upper eye, its middle rays highest, anterior not elevated; anal fin not 
preceded by a spine, its middle rays highest; caudal fin very sharply double-truncate, as long as head; 
pectorals short, that of left side the longer, about three-fourths length of head; ventral of colored side on 
ridge of abdomen, the membrane of its last rays nearly reaching base of first ray of anal; ventral of blind 
side longer than the other, one-half length of head, inserted farther forward than that of colored side; 
vent lateral, with well-developed anal papilla. Scales thin, large, ctenoid on colored side, smooth on 
blind side, those on middle part of body larger; head entirely scaly, except the snout and interorbital 
ridge; rays of vertical fins with scales on basal half, on colored side; lateral line developed equally on 
both sides, nearly straight. 
Color, olive-brown, with some darker blotches, most distinct in larger specimens; vertical fins 
finely mottled and streaked with black and gray; pectoral and ventral on left side spotted. 
Tropical America on both coasts, north to Cerros Island and North Carolina, south to Panama 
and Rio Janeiro; recorded from Charleston, Cedar Keys, New Orleans, Galveston, Beaufort, N. C., 
Mazatlan, Panama, from localities along both sides of coast of Lower California, and from several 
places in Florida. Specimens before us are from Mayaguez, Palo Seco, and Arroyo, Porto Rico. 
Etropus crossotus Jordan & Gilbert, Proe. U. S. N. M. 1881, 364, Mazatlan; Jordan & Evermann, 1. e., 2689, 1898. 
Family LXXIV. SOLEIDdi. The Soles. 
Body oblong or elongate, usually scaly; mouth very small, much twisted toward eyed side; teeth 
in villiform bands, very small or obsolete; eyes small, close together, with or without a bony ridge 
between them; edge of preopercle adnate, concealed by skin and scales; gill-openings narrow, gill- 
membranes adnate to shoulder-girdle above; pectoral fins small or wanting; ventral fins small, one or 
both sometimes wanting. 
Small fishes living on sandy bottoms, similar to the Pleuronecticlx in structure, but much degraded, 
the fins and teeth having lost many distinctive qualities; the vertebra? usually in increased numbers. 
The soles are numerous in the warm seas, and those of sufficient size are valued as food. They 
comprise about 12 genera and 150 species. They are naturally divisible into 3 subfamilies, each quite 
distinct from the others, and possibly independently descended or degraded from normal Pleuronectidx. 
The North American species belong to 2 subfamilies, very different one from the other. The Achirinx, 
or American soles, are apparently allied to the Pseltinx, the ventral fin of eyed side extending along 
ridge of abdomen. The Soleinse, or European soles, show in the insertion of ventral and in other 
respects a strong resemblance to the Pleuronectinx. The more aberrant Cynoglossinx, or tongue-fishes, 
are perhaps degraded Soleinse, but the eyes are sinistral, as in the Pseltinx. In the Soleinx and Achirinx 
the eyes are dextral, as in the Pleuronectinx. 
Achirin;e: 
I. Soles with eyes on right side and separated by a distinct bony ridge; ventral with long base confluent with anal. 
Body oblong or ovate, with coloron rightside; eyes moderate or small, upper eye usually more or less inadvance 
of lower; mouth small, more or less twisted toward blind side; teeth little developed, in villiform bands; edge 
of opercle adnate, usually concealed by scales; gill-openings more or less narrowed, gill-membranes adnate 
to shoulder-girdle above; blind side of head usually with fringes; pectoral fins small, sometimes wanting; 
ventral fins developed, one or both of them sometimes obsolete; scales usually ctenoid, rarely wanting, 
lateral line straight, usually single; right ventral with extended base, confluent with anal fin. 
a. Gill-openings of moderate extent, confluent below; vertical fins well separated; body ovate in outline, depth nearly 
one-half length; pectoral fins rudimentary or wanting; lateral line straight; scales well developed, etenoid 
more or less enlarged on head, those of blind side of head with fringes; vertebra? about 28 Achirus, 159 
aa. Gill-openings very small, separate, each reduced to a small slit below angle of opercle; right ventral beginning at 
chin; pectoral fins minute or wanting; lateral line straight; snout dilated, dorsal beginning upon it. 
