BULLETIN OF THE UNITED STATES FISH COMMISSION. 331 



little elev'ated. Second dorsal aud anal similar to each other, their 

 bases elongate, their rays high, the last, when depressed, nearly reach- 

 ing to the base of the candal. Caudal tin of moderate length, sharply 

 pointed, the middle rays produced, as long as from snout to base of 

 pectoral. Pectoral fins short and broad, the rays all slender and flue, 

 the upper not silk-like, the fin about three-tifths length of head. Yen- 

 trals fully united, the basal membrane very delicate, but M^ell developed, 

 the fin pointed in outline. Insertion of ventrals under axil of pectorals. 



Head, 3-^ in length ; depth, 5. D. VII-IC ; A. 17 ; Lat. 1. about 05. 



Coloration in life: Light olivaceous, the belly silvery ; above thickly 

 punctate with pale dots ; sides very thickly covered with golden-green 

 specks, visible under the lens ; back with six pairs of golden-green spots 

 on each Mde of the dorsal fin, each nearly as large as the pupil ; those of 

 the first pair approximate, in front of the spinous dorsal ; the second 

 pair is under middle of spinous dorsal; the third pair under end of 

 spinous dorsal ; the fourth pair under first third of second dorsal ; the 

 fifth pair under the second third; the sixth pair (faint and often wanting) 

 under last rays of soft dorsal. Sides of head and anterior half of bodj' 

 with wide streaks and bars alternately of purplish blue and golden 

 bronze; those on cheeks longitudinal; those on opercle extending 

 obliquely upwards and backwards ; those on body vertical. All these 

 markings disap]:>ear in spirits, leaving the fish plain light olive, usually 

 with a broad silvery cross-bar behind pectorals. First dorsal transpar- 

 ent dusky, second dorsal with about three series of light blue s])ots. 

 Anal with a tinge of light pink and a narrow margin of greenish white. 

 Caudal yellowish green below, dusky above; a very conspicuous narrow 

 bright red streak from the lower end of the base to the tip of the 

 5th or Gth ray from the bottom, thus crossing the rays obliquely. Ven- 

 trals glaucous bluish. * 



This species is very common in the rock-pools in the Bay of Panama, 

 where it hides very closely among the rocks. Numerous specimens 

 were obtained from 2^ to 3J inches in length. 



This species has the dentition of the group called Eiictcnor/ohius, with 

 the squamation similar to that of the species which have been called 

 EucydogoMus. It may for the present be referred to GoMus, although 

 it is not a member of that genus as restricted by Bleeker, Gill, and 

 Glinther. In Bleeker's system it would form the type of a new " genus." 



IT. Microdesmus retropinnis, sp. uov. (29(3G5.) 



Body very elongate, compressed, tapering somewhat from front of 

 dorsal to caudal peduncle. Head very small, rapidly tajiering forward 

 from occiput; upper profile with a noticeable depression behind the 

 orbits, the outline thence to snout strongly convex. 



Mouth very small, somewhat oblique, the fleshy tip at symphysis of 

 lower jaw projecting much beyoiul the premaxillaries; gape scarcely 

 reaching vertical from orbit. Teeth small, apparently in a single series 



