M ALACOPTERYG II.
F a m i ly . S IL U R ID ® .
1 . P iM E L O D U S G R A C IL IS. Val.
Pimeloclus gracilis, Val. in D’Orb. Voy. dans I’Ainer. Merid. Atl. Ichth. PI. 2. fig. 5.
--------------------------Cuv. et Val. Ilist. des Poiss. tom. xv. p. 134.
F o rm .— O f a slender elongated form, the body compressed behind the dorsal. G reatest depth contained
about seven and a half times in the entire length: thickness at the commencement of
the dorsal a little less than the depth. Head, measured to the gill-opening, rather more than
one-sixth of the entire length : its breadth two-thirds of its own length. H elm et smooth, and
n ot very conspicuous, though with its whole surface finely w rinkled: its breadth behind the
eyes rather more than one-third of its length, measuring this last from the end of the snout to
the further extrem ity of the interparietal process. T he solution of continuity extends back
nearly to the base o f the process just mentioned,which last is narrow and lanceolate, three
times as long as broad at its base, but not reaching to the buckler, or triangular plate in front
of the dorsal, by one-third of its own length. The buckler itself is not very large, but sufficiently
obvious.
Profile sloping gradually downwards in nearly a straight line from the beginning of the
dorsal to the end of the snout: this last depressed and rounded horizontally in the form of a
semicircle. M outh wide, but very little cleft, the commissure not reaching half way to the
eye. U pper jaw projecting a very little beyond the lower. In each a band of very fine
velutine teeth; but none on the vomer or palatines. Tongue smooth, and fastened down all
round. Six barbules; the maxillary pair very long, reaching to the commencement of the
anal fin ; of the submandibular pairs, the exterior reach one-thir^ beyond the insertion of the
pectorals ; the interior are only half the length of the exterior. Eyes round, of moderate size,
their diam eter four and a half times in the length of the head, situate in about the middle
of the length: distance from one to the other one diameter and a quarter. L ateral line
nearly straight throughout its course, dividing the body longitudinally into two nearly equal
portions.
Pectorals not quite equalling the length of the head, and a little less than one-sixth of the
entire length : the spine very little shorter than the soft rays, very strong, with sharp teeth on
its inner edge, but the outer edge only granulated, or with a few slight serratures towards the
extremity. T he humeral bone seen above the pectoral projects backwards in the form of a
spinous lamina, but does not appear through the skin ; it equals half the length of the pectoral
itself. T he dorsal commences at one-fourth of the entire length, and is of a somewhat rectangular
form, the soft rays not decreasing much backw ards: its length equals four-fifths of the
depth of the body, and two-thirds of its own height. T he spine is not so strong as that of the
pectoral, and with only a few small serratures on the outer edge near the tip. T he space
between the dorsal and the adipose a little exceeds the length of the former. T he i
FISH . ^ ^ ‘
itself is twice the length of that fin ; very low at first, but gradually rising, until, before its
termination, it becomes equal to between one-half and one-third of the depth. T h e vent is m
the middle of the entire length, caudal excluded. Anal short, and ju st beneath the middle of
the adipose, there being about one-fourth of this last fin in advance o f it as well as behind i t ;
the first four rays simple, but apparently all articulated, tbe first two or three very m inute and
not easily observed. C audal forked for two-thirds of its len g th ; the upper lobe a little longer
than the lower, and contained live and a half times in the entire length. V entrals immediately
beneath the last ray of the dorsal; a little shorter than the pectorals, and not reaching
to the anal by half their own length.
D. 1/6; A. 14 or 15; C. 17, & c.; P . 1/9; V. 6 .
Length 5 inches 2 lines.
C oLons—(/» spiWis.) Brownish, inclining to silvery in some places; a dusky fascia formed of
dots along the lateral line. Dorsal rather dusky at the base, and with the upper portion also
dusky between the ray s: a dusky spot on the anterior p art of tbe adipose.
Habitat, Rio de Janeiro.
This species was taken by Mr. Darwin in a running brook at Rio de Janiero.
It approaches on the whole so nearly the P . gracilis of D'Orbigny, that I can
hardly suppose it to be distinct. Yet there are some slight differences observable
in this specimen. It has more anal rays ; the adipose appears'shorter; and
the upper lobe of the caudal is not so prolonged, though possibly it may be worn
down. Also D ’Orbigny’s figure appears to want the dusky stains on the dorsal
and adipose fins. If it be not that species it must be new, as there is none other
described by Cuvier and Valenciennes with which it will assimilate better.
2 . P iM E L O D U S EXSUDANS. Jeii.
P . corpore parum elongato, altitudine quintam partem longitudinis esquante: galea
Imvi, inconspicua, processa interparietali haud clypeum parvum pradorsalem a ttin gente
: poris paucis huccalihus amplis, serie obliquà dispositis : m axillis eequalihus :
maxillaribus haud analem attingenlihus : lined laterali prim um deflexei.
deinde rectii: pinnis dorsali et anali brevihus; adiposa dorsali haud duplo longiore :
caudali profundh bifurca, lobis eequalihus: spind pectorali m argine interno fo r tite r
dentato.
D. 1/7 ; A. 13 vel 14; C. 17, &c. ; P. 1/8 ; V. 0.
L o n g . u n c . 3 . lin . 6.
F o rm .—In some respects resembling the last species, but the body much less elongated, the depth
and thickness remaining the same. T h e depth is about one-fifth of the entire length; the
head rather more than onc-fifth. T he helm et is scarcely so much wrinkled, and the inter-
parictal process not so long, reaching only half-way to the buckler, which last is smaller and
less obvious. T he solution of continuity of the bones o f the cranium appears to extend back