PLATE XXIX. fig. 1.
_A. elongatus: lateribus supra pallide olivaceis, fasciis transversis
abbreviatis, lineisque longitudinaliter undantibus, nigris;
lateribus infra argenteis: pinnis dorsalibus et caudali punctatis;
pinnis, reliquis, et lineâ laterali, albidis._
B. 6; D. 8—25; A. 1/22; C. 14, et 6 brevioribus; P. 22; V. 1/5.
LONG. unc. 3. lin. 1.
FORM.—Elongated; the depth about one-sixth of the entire length; the
thickness two-thirds of the depth. depth. Head four and a half times
in the length. Profile falling very gradually at first, but more
rapidly in advance of the eyes, causing the snout to appear rather
obtuse. Mouth small: maxillary slender, hardly reaching to a
vertical line from the anterior margin of the orbit: upper jaw
slightly longer than the lower, and very protractile. Teeth very
minute, forming a narrow velutine band: a patch on the chevron of
the vomer scarcely visible, but capable of being very distinctly
felt; none apparent on the palatines. Eye one-fourth the length of
the head, and distant one diameter from the end of the snout; the
interocular space rather less than the diameter. Snout slightly
indented, or furrowed out in front of the eyes. A series of
impressions on the lower jaw, and along the limb of the preopercle,
but much less obvious than in the next species, and not distinctly
porous. Preopercle with the ascending margin vertical, the angle at
bottom rounded; the limb broad and distinctly marked, with the
boundary line between it and the cheek slightly elevated into a
ridge. The opercle, with its membrane, produced backwards in an
angle, the subopercle being visible beneath. The branchial membrane
six-rayed, and fastened to the isthmus underneath, the aperture
commencing beneath the ascending margin of the preopercle.
[Illustration:
_Fish Pl. 29 Appendix._
_Waterhouse Hawkins del._
]
_1. Aphritis undulatus._ _Nat. Size._
_2. Iluocœtes fimbriatus._ „
_2a. „ Magnified View of Teeth._ „
_3. Phucocœtes latitans._ „
_3a. „ „ Teeth._ „
Lateral line commencing at the upper angle of the gill-opening, and
following the curvature of the back at one-fourth of the depth, and
preserving this direction throughout its course, not falling to the
middle before losing itself in the caudal. Scales small, covering
the whole head and body, except the snout in front of the eyes, the
jaws, and the limb of the preopercle. The free portion of each scale
marked with several small concentric circles, the free edge finely
ciliated: the basal portion with a fan of seven striæ, and the
spaces between these deeper striæ with minuter striæ running
transversely: the basal margin cut square.
Pectorals attached rather low down, and a little posterior to the
terminating angle of the opercle; their length about three-fourths
that of the head: the fourth to the eighth rays longest; the first
ray only half the length of the second; the first two, and the last
three or four, simple; the rest branched. Ventrals about four-fifths
the length of the pectorals, and in advance of those fins by nearly
half their own length; their spine very distinct. First dorsal
short, commencing immediately above the insertion of the pectoral:
all the spines very slender, with the intervening membrane delicate;
the second longest, equalling about half the depth; the third and
following ones gradually decreasing. Second dorsal long, separated
from the first by a very small interval, and occupying a space just
equal to the distance between its commencement and the end of the
snout: the rays gradually decreasing in length from the anterior
ones, which equal three-fourths of the depth; all simple, or if
branched, only so at their extreme tips. The interval between the
second dorsal and the caudal contained eight and a half times in the
entire length. Anal commencing under the sixth ray of the second
dorsal, or exactly at the middle point of the entire length, caudal
excluded; extending a trifle beyond the second dorsal, but in other
respects answering to that fin. Caudal square when spread, but very
slightly notched when the rays are close; contained six and a half
times in the entire length; the principal rays branched.
COLOUR.—(_In spirits._) Back and upper half of the sides pale
olivaceous, with about seven or eight abbreviated, transverse, dusky
fasciæ; beneath these are two irregular lines undulating
longitudinally in a zig-zag manner, and having rather a tendency to
meet at the angles, so as to form a connected longitudinal chain of
diamond-shaped links. Lower portion of the sides and abdomen
silvery. Tubal pores of the lateral line white, making this line
very evident. Dorsal and caudal fins speckled with small dusky spots
and points. Pectorals, ventrals, and anal, quite plain, and whitish.
A _second specimen_ in the collection exactly resembles the above,
except in being not quite so large, and in having a ray less in each
of the two dorsal fins.
Habitat, Chonos Archipelago, W. coast of S. America.
The genus _Aphritis_ was first established by M. Valenciennes, in the
appendix to the eighth volume of the “Histoire des Poissons,” for the
reception of a small Percoid fish obtained by MM. Quoy and Gaimard in
Van Dieman’s Land, inhabiting fresh-water. The species above described,
which was taken by Mr. Darwin in Lowe’s Harbour, South of Chiloe,
appears to be referable to the same genus. It differs, however, in many
respects from the _A. Urvillii_, the only one which Valenciennes has
noticed. The relative situation of the first dorsal with respect to the
pectorals, and of the anal with respect to the second dorsal, is
different: there are fewer rays in the anal, and more in the second
dorsal: the upper, instead of the lower jaw, as represented in
Valenciennes’s figure, is rather the longest; neither can I discern any
teeth on the palatines, though there is a patch of very minute ones in
front of the vomer.
That this species really belongs to _Aphritis_, would seem indicated not
merely by the aggregate of its external characters, but by the internal
structure also, which was examined in one of the two specimens brought
home by Mr. Darwin, and found conformable to what is stated by
Valenciennes, in this respect, of the _A. Urvillii_. The stomach is
large, with four very distinct cœcal appendages, and there is no
air-bladder.
The _A. undulatus_, which I have so named in reference to the undulating
longitudinal lines on the sides, is very Cypriniform in general
appearance, and not altogether unlike the common minnow, _Cyprinus
Phoxinus_.