FORM.—Scarcely differing from the _M. glutinosa_, but apparently
rather more slender in proportion to its length. Mouth and cirriform
appendages the same. Branchial orifices two, very near together,
placed beneath, at a little beyond one-fourth of the entire length.
A very conspicuous row of pores along each side of the abdomen. The
tail seems somewhat sharper than in the _M. glutinosa_, and the rays
of the low fin which turns round its extremity rather more distinct.
Vent distant from the end of the tail rather less than one-eighth of
the entire length.
Length 11 inc. 6 lin.
COLOUR.—“Above coloured like an earth-worm, but more leaden; beneath
yellowish; head purplish.”—D.
Habitat, Tierra del Fuego.
Mr. Darwin obtained this species by hook amongst the kelp, in Goree
Sound, and other parts of Tierra del Fuego, where he observes it is
abundant amongst the rocky islets. Its extreme southern locality would
suggest the idea of its being distinct from the _M. glutinosa_ of the
northern seas; yet the differences between the two, upon comparison, are
very slight, and, if it really be so, as I have ventured to consider it,
it requires an examination of more specimens to lay down its exact
specific character.
Mr. Darwin has made some interesting remarks on the habits of this fish.
He observes that it is “very vivacious, and retained its life for a long
time; that it had great powers of twisting itself, and could swim tail
first. When irritated, it struck at any object with its teeth; and by
protruding them, in its manner, much resembled an adder striking with
its fangs. It vomited up a _Sipunculus_ when caught.” He adds, that he
“observed a milky fluid transuding through the row of lateral pores.”