Diodon nycthemerus, _Cuv._ Mém. du Mus. tom. iv. p. 135. pl. 7.
A species of _Diodon_ in Mr. Darwin’s collection, the number attached to
which has been lost, and of which the locality is in consequence
unknown, appears referable to the _D. nycthemerus_ of Cuvier.
The spines are long, measuring three quarters of an inch in length;
round, sharp, and not very close together. There are five in the front
row between the eyes, seven in a transverse row between the pectorals,
and ten or eleven between the snout and the dorsal in a longitudinal
one: none exactly on the upper part of the tail, but one on each side
of the base of it, a little below the termination of the dorsal fin,
and a corresponding pair still lower down. The spines on the belly are
shorter, and rather closer together than those on the back. One of
those on the back in this specimen is accidentally forked.
The true teeth appear on the surface of the jaws like minute scales,
as in several species of the genus _Scarus_.
The fin-ray formula is as follows:
D. 13; A. 13; C. 9; P. 20.
Length 5 inches 6 lines.
The colours, so far as can be judged, the specimen being in spirits and
not in very good condition, answer to Cuvier’s description of them with
tolerable exactness.