292 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
forming a cup-shaped disk, only about two-fifths posterior edge free from belly; caudal rounded. 
Scales very small, ctenoid, densely covering entire body except a broad strip on belly; posterior portion 
of nape with very fine scales; entire head naked. 
Color, dark-brown or olivaceous on head, sides, and back; under parts pale; fins all pale, anal 
with a narrow darkish margin; caudal somewhat dark; no dark vertical bars on body and none at base 
of pectoral; no H -shaped figure at base of caudal. 
This species is close to S. plumieri, from which it differs chiefly in color, the more complete 
squamation, the shorter pectoral, and the nonfilamentous character of dorsal spines. Known only 
from the type, 3.63 inches long, from the Rio de Caguitas at Caguas, Porto Rico. 
Sicydium caguitse Evermann & Marsh, Rept. U. S. P. C. 1899 (Dec. 19), 355, Rio de Caguitas, Caguas, Porto Rico. 
246. Sicydium plumieri (Bloch). Sirajo. 
Head 4 to 4.6; depth 4.5; eye 6 to 7 in head, 2 to 3 in interorbital width; D.vi-i, 10; A. i, 10; scales 84. 
Teeth in upper jaw long, slender, bent inward at right angles, only tips protruding from gums. Front 
teeth of lower jaw not larger than those behind; a single row of inconspicuous papillae on gum beneath 
upper lip, a large median papilla above maxillary suture; a median cleft in upper lip. Pectoral longer 
than head; third, fourth, and fifth dorsal spines produced into long ribbons, the fourth, which is longest, 
being 2 to 3 times height of body. Body usually covered with small scales, reduced in size on neck 
and belly; frequently almost naked, scales present only on posterior part of body. Caudal deeply 
emarginate. 
Color, olive or violet-brown, with about 7 more or less distinct dark vertical bars; a dark bar at 
base of pectoral; dorsal with irregular dark markings; anal fin with a dark marginal band, sometimes 
edged with white; an H -shaped figure on base of caudal fin, and a black bar on its posterior half. 
An inhabitant of the fresh waters of the West Indies. Not obtained by us in Porto Rico, but 
recorded by Professor Poey. 
Gobius plumieri Bloch, Ichth., 125, pi. 178, fig. 3, 1786, Martinique; on a drawing by Plumier. 
Sicydium siragus Poey, Memorias, II, 278, 1861, Santiago de Cuba. 
Sicydium plumieri Poey, Fauna Puerto-Riquena, 338, 1881; Jordan & Evermann, 1. c., 2206, 1898. 
Genus 138. GOBIUS (Artedi) Linnaeus. Gobies. 
Body oblong or elongate, compressed behind. Head oblong, more or less depressed. Eyes high, 
anterior, close together; opercles unarmed. Mouth moderate. Teeth on jaws only, conical, in several 
series, those in outer row enlarged; no canines. Isthmus broad. Shoulder-girdle without fleshy flaps 
or papillae. Skull depressed, abruptly widened behind eyes and without distinct median keel. Scales 
moderate, ctenoid, permanently covering body; cheek usually naked; belly generally scaly. Dorsal 
with 6 rather weak spines; pectoral well developed, upper rays sometimes very slender and silky; 
ventrals completely united, not adnate to belly; caudal fin usually obtuse. 
The genus Gobius, as here understood, comprises a very large number of species more or less 
closely related to the European type of the genus, Gobius niger, and its American relative, Gobius 
soporator. An examination of skulls or skeletons of numerous European and American species shows 
a remarkable uniformity in most respects. The general form and structure of the cranium is the same 
