to each other, and also to the space ju st alluded to. From the end of the second dorsal to the
commencement of the caudal is exactly one-sixth of the entire length. The posterior h alf of
the anal nearly answers to the second dorsal, but the two fins do not term inate exactly in the
same line, the dorsal extending a little the furthest. Caudal forked for about h alf its length.
Pectorals about two-thirds the length of the head. V entrals attached at a point beyond the
extremity of the pectorals. B readth of the silver band about one-fifth the depth of the body.
Colour.— N ot noticed in the recent state. In spirits, the back and sides above the silver band
are brownish, with the contour of each scale marked out by black dots. All below the band
appears to have been silvery. The band itself is not very brilliant. B oth the dorsals, as well as
the caudal, are dusky: anal and ventrals pale.
A second specimen does not differ from the above, excepting slightly in the fin-ray formula,
which is as follows :
D. 5—1/10; A. 1/15; &c.
H abitat, Valparaiso.
This species was found by Mr. Darwin at Valparaiso in fresh water, in the
month of August. It would seem to be nearly allied to the A . laiiclavia of Cuvier
and Valenciennes, brought from the same locality by M. D ’Orbigny ; but, judging
from the short description in the “ Histoire des Poissons,” it is more elongated, and
has the head longer in relation to the depth of the body ; also has the silver band
narrower. In the A . laticlavia, the head is said to be equal to the depth, and to
be contained six times in the entire length ; the breadth of the silver band to be
greater than in any other species. In the A . microlepidota, the depth is
one-eighth and the head one-sixth of the length : the silver band not broader than
in the A . argentinensis and some others. The colouring also of the fins appears
different in the two species.
3 . A t h e r i n a i n c is a . Jen.
P l a t e X V I. Fig. 2. Nat. size.
Fig. 2. h. Twice nat. size.
Fig. 2. a. Magnified scale.
A . g ra cillim a ; corporis altitudine partem v ix nonam, capite sextam , hngitudinis^
cequante: oculis mediocribus: m axillis aqualibus, valde protractilibus ; commissurd
p rim um horizontali, posterius dejlexd: dentibus velutinis, in m axilU inferiore
m inutissim is: dorsali prim a omnino pone ventrales reclinatas locata: squamis
mediocribus, seriebus longitudinalibus duodecim ad m axim um dispositis, marginibus
liberis inciso-creuatis : v ittd laterali nitidh argentea.
D. 5— 1/8 ; A. 1/17 ; C. 17; P . 12 ; V. 1/6.
D . 6— 1/9; A. 1/19; &c.—
D. 6—1/10; A. 1/19; &c.—
L o n g . u n c . 2 . lin . 6.