_M. viridescenti-fuscus, dorso saturatiore; hoc, et lateribus, et
pinnis, nigro levissimè irroratis, immaculatis; ventre niveo; oculis
majusculis._
D. 10; A. 16; C. 16, &c.; P. 13; V. 7.
LONG. unc. 2. lin. 5.
FORM.—Very little difference in form between this and the last
species. The eyes, however, are decidedly larger, measuring in
diameter one-third the length of the head. The head itself also
appears somewhat longer, being nearly one-fifth of the entire
length. The anterior teeth on the tongue do not seem much larger
than the others. Fins similar.
COLOUR.—(_In spirits_). Greenish-brown, deepening in tint at the top
of the back. Back, sides, and fins, immaculate, but thickly powdered
with minute dark specks, scarcely visible except under a lens. These
specks give the fins a more dusky appearance than they possess in
the last species. The belly appears to have been white.
A _second specimen_ does not differ from the above in any respect,
except in being rather smaller, and scarcely more than two inches in
length.
Habitat, Tierra del Fuego.
This species was taken by Mr. Darwin in alpine fresh-water lakes in
Hardy Peninsula, Tierra del Fuego. I have no hesitation in considering
it distinct from the last, as there are two specimens exactly similar,
both shewing a larger eye, and an entire absence of all approach to
spots; while the whole surface of the back and sides is thickly
irrorated with dark specks, a character which does not appear in the
plain varieties of the _M. maculatus_.
3. MESITES ATTENUATUS. _Jen._
PLATE XXII. fig. 5.
_M. viridescenti-fuscus, ventre vix pallidiore; dorso, et lateribus,
pinnarumque radiis, sparsim nigro levissimè irroratis, immaculatis:
corpore prægracili, anticè attenuato; capite et oculis minoribus._
D. 11; A. 17; C. 16, &c.; P. 12; V. 7.
LONG. unc. 2. lin. 6.
FORM.—Rather more slender than either of the last two species, the
body more attenuated anteriorly; the head also smaller, though
scarcely shorter. Mouth and eyes both smaller; the diameter of the
latter not more than one-fourth of the length of the head. Teeth
also rather more minute as well as more numerous. The fins are
similar, except that the ventrals appear to stand rather more
forward, being attached exactly in the middle of the entire length,
excluding caudal: the distance from their insertion to the
commencement of the anal is more than twice their own length. The
outer rays of the caudal are worn, but there was probably a shallow
notch when entire: the short accessory rays are very numerous, and
form a very distinct fringe along the upper and lower edges of the
fleshy part of the tail.
COLOUR.—(_In spirits._) Greenish-brown, much more uniform than in
either of the last two species, not deepening on the back, and
scarcely becoming paler underneath. The back sides, and rays of the
fins, are finely irrorated with dusky specks, as in the _M.
alpinus_, but not to the same extent, the specks being more thinly
scattered, and here and there scarcely visible. From the same cause
the fins appear paler.
Habitat, Bay of Islands, New Zealand.
This, which is a very distinct species of this new genus, was taken by
Mr. Darwin in fresh-water in the Bay of Islands, New Zealand. It is well
characterized by its more attenuated head and smaller eye, than those of
either of the two others.