ATOPICHTHYS ESUNCULUS. 327 
Atopichthys esunculus sp. n. 
Plate LXV. figs. 2, 2a. 
DG UpCAG Ss P13) Vio83 (C.20- 
The form of this species closely resembles that of HL. Costai as given by 
Kaup, 1856, Cat. Apodal Fish, Pl. XVI., fig. 3. 
The body is much compressed and attains its greatest depth, which is 
about one seventh of the total length, at about three fourths of the distance 
from the snout to the tail, whence it gradually tapers to the head. Body 
cavity very long, close upon seven eighths of the total. 
Head small, comparatively narrow, subconical, near one twelfth of the 
entire length, convex on the crown and on the top of the snout, moderately 
blunt and rounded in front. Somewhat pointed, arching upward above the 
mouth, shorter than the eye. Eye large, one third as long as the head, 
longer than the snout, lateral. Mouth large; maxillary extending below 
little more than half of the eye. Teeth on the lower jaw large, slender, 
acicular, compressed, inclined forward; on the upper jaw smaller, very 
slender, vertically directed. Nostrils small, in front of the eyes, midway 
to the end of the snout. Gill openings wide, passing from in front of the 
pectoral base down and forward to below the eyes. 
Pectoral fins small, of about thirteen rays, reaching the eye. 
Ventrals small, of eight rays, bases below the thirty-fifth transverse 
muscle segment, which is nearly in the middle of the length. 
Dorsal of sixteen or seventeen rays, shorter backward, the first above 
the fifty-fourth muscle-segment or about the beginning of the posterior 
fourth of the total. Anal short, of eight rays, close to the caudal, originat- 
ing below the sixty-seventh muscle-band. Caudal short, rather deep, 
deeply forked, of twenty-five rays. Vent below the sixty-sixth muscle- 
segment. 
Translucent or transparent; with black pigment in a streak of puncticu- 
lations along the upper edge of the intestine, in a dot on the caudal pedicel 
forward of the bases of the rays, and in a transverse band across the bases 
of eight or ten of the inner rays of the caudal. 
“Off Acapulco, Apr. 13, 1891.” 
