FISH. 41 
Famity.—SCIZNIDZ. 
OrouirHus GuATUCUPA. Cuy. et Val. 
Otolithus guatucupa, Cu. et Val. Hist. des Poiss. tom. v. p. 56. pl. 104. 
Form.—Elongated, with the back only very slightly elevated beneath the first dorsal: in advance 
of that fin the dorsal line is nearly straight, and continuous with the profile. Greatest depth 
contained exactly four times and a half in the entire length. Head long, contained three and a 
half times in the same. Lower jaw projecting considerably beyond the upper, and ascending 
to meet it. Two strongly developed curved canines at the extremity of the upper jaw ; the rest 
of the teeth in this jaw consist of a single row of fine card, nearly equal throughout: in the 
lower jaw there are no canines, but one similar row of card, rather stronger than those above, 
and not equal, the smallest being in front, and those at the sides becoming gradually larger 
as they extend backwards. No vestige of scales on the lower jaw, lips or maxillary ; but the 
suborbital is covered with bright silvery scales. Eye full, and moderately sized; its diameter - 
one-fifth the length of the head; its distance from the end of the upper jaw equalling the 
diameter. Margin of the preopercle with a few indistinct strize and obsolete denticulations. 
Opercle with two flat points not much developed. Lateral line very distinct, commencing at 
rather less than one-third of the depth, but curving gradually downwards to one-half; continued 
to nearly the extremity of the caudal; each scale marked with an elevated line, from which 
there proceed one or two small ramifications on each side. 
First dorsal triangular, with the first spine very short, the fourth longest, the fifth and 
succeeding ones gradually decreasing, the last or tenth being shorter than the first. Second 
dorsal almost contiguous, its spine or first ray about equalling the first ray of the first dorsal : 
this fin is more than half as long again as the first, and the rays are nearly even. The anal 
commences further back than a point opposite the middle of the second dorsal; there are in 
reality two spines in this fin, but the first is so extremely minute as to be almost microscopic, 
and not seen, unless very carefully sought for ; the second or principal spine 1s weak, and rather 
more than one-third the length of the soft rays. Caudal apparently square, but the rays being 
worn at the tips, its exact form cannot be determined. The second dorsal, as well as the anal 
and caudal, are partially covered with small scales, which, however, are not very obvious.: 
Pectorals narrow and rather small, being scarcely more than half the length of the head. 
Ventrals placed a little further back, and rather shorter than the pectorals. 
B. 7; D. 10—1/20; A. 1/8; ©. 17; P. 16; V. 14. 
Length 9 inc. 9 lines. 
CoLour.— Silvery white, above iridescent with violet purple and blue.’”—D. Mr. Darwin has not 
noticed the dark transverse lines, which descend from the back obliquely forwards, as repre- 
G 
