338 PROCEEDIXGS OF UNITED STATES NATIONAL MUSEUM. 



Ill tlie following paper are described the following genera and species, 

 apparently never before observed: 



Thyris, n. g. ) 



Hypsicometes, n. g. Merluciidcef ' ' 



MonoJene sessilieauda, n. s. 



Cltharichthrjs arctifrons, n. s. 



Citharichthys unicornis, n. s. 



Thyris pellucidus, n. s. 



Macrurus carminatus, n. s. 



Sypsicometes gohioides, n. s. 



Peristedium miniatum, n. s. 



I am greatly indebted to Mr. Frederick Gardner, jr., who has assisted 

 in the preparation of this paper. 



Monolene,* new geuus. 



A genns of plenronectoid fishes with thin elongate body and sessile 

 candal fin. Eyes npon 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 npon 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 

 pectoral ; on the blind side straight, rising slightly as it approaches the 

 region of the gill-opening. Gill-rakers few, feeble. Vertebrae 43. 



Monolene sessilicauda, new species.. 



Extreme length of specimen described 0.156™.t ^ 



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: ^uoi^of ^single; wAev;/ ^ an arm. 

 tNo. 26004. 



