_P. cæruleo-argenteum, operculo nigro-marginato: pinnâ, dorsali
subæquali, spinis ultimis radiis articulatis paulo brevioribus;
anali spinâ, secundâ forti, longitudinaliter striatâ, radiis
articulatis duodecim: preoperculo rectangulato, margine adscendenti,
leviter denticulato, basali integro: vertice, buccis, et ossibus
opercularibus, squamatis; rostro ultrà nares, suborbitalibus, et
maxillis, nudis; squamis corporis ciliatis: pinna caudali furcatâ._
B. 7; D. 12/15; A. 3/12; C. 17, et 4 breviores; P. 20; V. 1/5.
LONG. unc. 10. lin. 11.
FORM.—Form oblong-oval, much resembling that of the _Cantharus
griseus_. Body compressed, with the dorsal line slightly curved; the
profile descending from the nape more obliquely, and in a very
regular manner. Greatest depth beneath the commencement of the first
dorsal, contained not quite three times and three quarters in the
entire length: head rather less than one-fourth of the length. Mouth
protractile, but not wide, the commissure not extending to a
vertical from the anterior angle of the eye; when closed, the
maxillary retires beneath the suborbital, and only just the
extremity remains visible. Jaws equal; in each a narrow band of
velutine teeth, the outer row somewhat longer than the others,
particularly above, where they approach to card. Tongue, palatines,
and vomer smooth. Eyes moderate; their diameter rather less than
one-fifth of the length of the head; rather nearer the extremity of
the snout than the posterior margin of the opercle; the distance
between them equalling twice their diameter. Two small pores and a
fossule beneath the symphysis of the lower jaw, the latter very
distinct. Preopercle rectangular, the angle somewhat rounded; the
ascending margin nearly straight and finely denticulated, but the
denticulations hardly continued to the angle, and not appearing at
all on the basal margin. Opercle with two small flat points, but
very indistinct and almost lost in the membrane. Suborbitals large,
with their lower margins entire. Crown, cheeks, and pieces of the
gill-cover, covered with small scales; but not the snout in advance
of the nostrils and eyes, nor suborbitals, nor lower jaw.
Suprascapulars marked by a large scale, the margin of which is
nearly entire.
Lateral line following the curvature of the back at one-third of the
depth; each scale marked with an elevated line without
ramifications. A scale taken from above the lateral line is of a
somewhat rhomboidal form; the free portion very finely striated,
with the margin finely ciliated; the concealed portion with eight or
nine deeper and more distinct striæ, not meeting in the centre to
form a fan, and with the basal margin crenated. The scales on the
cheeks and opercle are smaller than those on the body, and almost
smooth.
The dorsal fin commences in a line with the posterior margin of the
opercle, and extends nearly the whole length of the back, rising
from a groove as in the _Sparidæ_: its height on the whole tolerably
uniform throughout: spinous portion occupying more than half the
fin; the anterior spines gradually increasing in length to the
fourth,[22] which equals rather more than one-third of the depth;
the succeeding ones nearly even, very gradually decreasing to the
last, which is about two-thirds the length of the fourth; all the
spines moderately stout: soft portion of the fin even, and rather
higher than the last spine. Anal commencing in a line with the third
soft ray of the dorsal, and terminating opposite to that fin: the
first spine short, but strong; second and third spines equal in
length, being about two-thirds the length of the soft rays, but the
second much stouter than the third; the second spine is also
distinguished from the others by having its surface longitudinally
striated: soft rays nearly even, and resembling those of the dorsal.
Caudal forked, with the upper lobe a trifle longer than the lower;
the basal half covered with minute scales. Pectorals narrow and
pointed, about two-thirds the length of the head, with a small fold
of loose skin in their axillæ. Ventrals placed a little further back
than the pectorals, and somewhat shorter; a long pointed scale in
their axillæ, nearly one-third their length.
COLOUR.—“Bluish silvery.”—D.—The colour, as it appears in spirit, is
nearly uniform bluish gray, and very similar to that of the
_Cantharus griseus_. The gill-cover has a dusky edging posteriorly.
_Second specimen._—Smaller than the above, and not quite so deep in
the body; the greatest depth contained a trifle more than four times
in the entire length; the nape in consequence less elevated, and the
profile less oblique. Eyes relatively a little larger, their
diameter rather more than one-fifth the length of the head.
Preopercle with the posterior margin not so rectilineal, approaching
to concave; the angle at bottom projecting in consequence a little
backwards; the denticulations not quite so distinct and regular. One
ray more in the soft dorsal.
D. 12/16; A. 3/12; C. 17, &c.; P. 19; V. 1/5.=
LONG. unc. 9. lin. 2.
COLOUR.—“Silvery; above, shaded with brown and iridescent with blue;
fins and iris sometimes edged with blackish brown. Flap of the
gill-cover edged with black.”—D.
Habitat, Galapagos Archipelago.
This species, which is undoubtedly new, may be known from most of those
described by Cuvier and Valenciennes by its greater number of soft rays
in the anal fin. The only ones which equal it in this respect are the
_P. Conceptionis_ and the _P. fasciatum_; from the former of which it
may be distinguished by its greater depth and nearly even dorsal, from
the latter by its plain colour free from all conspicuous bands and
markings. The dorsal notch is scarcely observable, the eleventh and
twelfth spines being nearly equal, and but little shorter than the first
soft ray. Its analogy to the genus _Cantharus_ among the _Sparidæ_,
which it resembles as well in colour as in general form, is very
striking. There are two specimens in the collection; the one described
first above having been taken at Chatham Island, the other at Charles
Island, in the Galapagos Archipelago.