338 -PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
In the following paper are described the following genera and species, 
apparently never before observed : 
Monoléne, n. g. 
Thyris, n. g. 
Hypsicometes, n. g. Merluciide ? 
Monolene sessilicauda, n. s. 
Citharichthys arctifrons, 0. Ss. 
Citharichthys unicornis, 0. 8. 
Thyris pellucidus, n. 8. 
Macrurus carminatus, n. Ss. 
Hypsicometes gobioides, n. 8. 
Peristedium miniatum, 0. s. 
; Pleuronectide. 
I am greatly indebted to Mr. Frederick Gardner, jr., who has assisted 
in the preparation of this paper. 
Monolene,* new genus. 
A genus of pleuronectoid fishes with thin elongate body and sessile 
caudal fin. Eyes upon left side very close together, and near to profile. 
Mouth moderate; the length of the maxillary less than one-third that 
of the head. Teeth minute in the jaws, in single series, nearly equal on 
both sides, though perhaps a trifle stronger on the blind side; absent 
on vomer and palatines. Pectoral fin upon blind side totally absent. 
Dorsal fin commences in advance of the eye upon the snout. Dorsal 
and anal rays simple. Caudal fin sessile, almost confluent with dorsal 
and anal. Ventrals normal. Scales rather large, ctenoid upon colored 
side, cycloid upon blind side. Lateral line marked; on colored side 
strongly and angularly curved above the anterior two-thirds of the 
pecteral; on the blind side straight, rising slightly as it approaches the 
region of the gill-opening. Gill-rakers few, feeble. Vertebree 43. 
Monolene sessilicauda, new species. 
Extreme length of specimen described 0.156™.+ 
The height of the body (38) is about three-eighths of the total length 
(without caudal), and is equal to twice the distance of the origin of the 
ventral from the snout (19); its height over the ventrals (25) is about 
five times the longitudinal diameter of the lower eye (5), the least 
height (8.5), at the base of the tail, slightly greater than the length of 
the lower jaw (8). The body is thin its greatest width (5) not exceed- 
ing the longitudinal diameter of the orbit. 
Scales subcircular, with irregular outline, about 2 millimeters in diame- 
ter, or in diameter about one-fourth (1.25) the diameter of the eye. The 
posterior edge of each scale upon the colored side is pectinate with about 
fifteen denticulations. The scales of the blind side are oval, non-pec- 
*Etymology: pévog=single; oAévy—=an arm. 
tNo. 26004, 
