MUSEUM OF COMPARATIVE ZOOLOGY. 193 



ceUnfus (Gill), Jordan and Gilbert. On account of its elongated ventral fin, 

 the triangular elongation of the anterior ra3's of the dorsal, and the highly 

 ctenoid character of the scales upon the colored side of the body, it seems 

 necessary to establish for it a new genus. 



A genus of pleuronectoid fishes, with elliptical body and pedunculate caudal 

 fin. Mouth moderate in size, and beneath the central axis of the body. Eyes 

 large upon left side, close together, the upper one nearly encroaching upon the 

 profile, the lower slightly in advance of the upper. Teeth in single series in 

 the jaws, about equally developed upon each side, much largest in front ; 

 absent on vomer and palatines. Pectoral fins somewhat unequal, that upon 

 the blind sitle about three fourths as large as its mate. The dorsal fin com- 

 mences sliglitly behind the anterior margin of the upper eye, and the first eight 

 rays are separated into a distinct subdivision of the fin, several of them being 

 much prolonged. 



Caudal fin pedunculate, rounded posteriorly. Sinistral ventral much elon- 

 gated. Scales small, ctenoid on colored side of body. Lateral line jjroniinent, 

 strongly arched over the pectoral, alike on both sides. Gill-rakers moderately 

 numerous, rather stout, subtriangular, pectinate posteriorly. Pseudobranchiae 

 well developed. Vertebrse 35. 



2. Notosema dilecta, new species. 



Diagnosis of Species. — Extreme length of specimen described 0.122 mm. 



The height of the body is contained twice in its total length, without caudal, 

 and is equal to twice the distance of the origin of the ventral from the snout. 

 The height of the caudal peduncle is one ninth of the standard body length. 



The length of the head is two sevenths of the standard length, and three 

 times the diameter of the eye. Width of interorbital area almost imperceptible. 

 Mandible reaching to middle of pupil of lower eye, its length equal to half that 

 of the head. Upper jaw contained twice and one half in length of head. 



The dorsal fin, beginning almost over the anterior margin of the eye, is com- 

 posed of about 68 rays, the longest of which are the second and third, which 

 are contained twice in the greatest height of the body, and which are almost 

 twice as long as the length of the base of the triangular division of the fin 

 to which they belong. 



The anal fin is made up of 54-56 simple rays, of which the posterior ones are 

 largest, as they are also in the main portion of the dorsal. It begins close to 

 the A'ent, at a distance from the snout equal to the length of the elongated 

 sinistral ventral. 



The caudal is pedunculate, its middle rays somewhate elongate, giving it a 

 wedge-shaped outline. 



The pectoral of the colored side is subtriangular, its length contained five 

 and one half times in the standard length. 



The ventrals are composed of six rays, that upon the colored side much pro- 

 duced in its anterior portion, its length more than three times that of its mate. 



VOL. X. — NO. 5. 13 



