i:
duck escapes when pursued by a dog; but I am nearly sure
that the steamer moves its wings alternately, instead of both
together, as in other birds. These clumsy, loggerheaded
ducks make such a noise and splashing, that the effect is
exceedingly curious.
Thus we find in South America three birds, which use
their wings for other purposes besides flight: the penguin as
fins, the steamer as paddles, and the ostrich as sails to a vessel.
The steamer is able to dive only a very short distance. It
feeds entirely on shell-fish from the kelp and tidal rocks;
hence the beak and head, for the purpose of breaking them,
are surprisingly heavy and strong. So strong is the head,
that I have scarcely been able to fracture it with my
geological hammer; and all our sportsmen soon discovered
how tenacious these birds were of life. When pluming
themselves in the evening in a flock, they make the same
odd mixture of sounds which bullfrogs do within the
Tropics.
In Tierra del Fuego, as well as at the Falkland Islands, I
made many observations on the lower marine animals,* but
they are of little general interest. I will only mention one
class of facts, relating to certain zoophytes in the more highly
organized division of that class. Several genera ( flustra,
eschara, cellaria, crisia, and others) agree in having singular
* W h il e a t th e F a lk la n d s , d u r in g th e a u tum n o f th e s o u th e rn h em is
p h e r e ,m o s t o f th e low e r m a r in e a n im a ls w e r e b re e d in g . I was su rp r is e d to
fin d o n c o u n tin g th e eggs o f a la rg e w h ite D o ris ( th i s sea-slu g was th r e e
a n d a h a lf in ch e s lo n g ) h ow e x tr a o rd in a rily n um e ro u s th e y w e re . F rom
tw o to five eggs (e a c h th r e e - th o u s a n d th s o f a n in ch in d iam e te r ) w e re
c o n ta in e d in a s p h e ric a l l i t t l e case. T h e s e w e re a rr a n g e d tw o d e e p in
tra n s v e rs e rows fo rm in g a rib b o n . T h e rib b o n a d h e re d b y its edge to th e
ro c k in a n o v a l sp ire . O n e , w h ic h I fo u n d , m e a su r e d n e a rly tw e n ty in ch e s
in le n g th a n d h a lf in b r e a d th . B y c o u n tin g h ow m an y b a lls w e re co n ta
in e d in a t e n th o f a n in ch in th e row , a n d h ow m an y rows in a n e q u a l
le n g th o f th e r ib b o n , o n th e m o s t m o d e r a te c om p u ta tio n th e r e w e re s ix
h u n d r e d th o u s a n d eggs. Y e t th is D o ris w a s c e rta in ly n o t v e ry com m o n :
a lth o u g h 1 was often s e a rc h in g u n d e r th e s to n e s 1 saw o n ly sev en in d i.
v id u als.
moveable organs, like those of Flustra avicidaria (found
in the European seas), attached to their cells. The organ, in
the greater number of cases, very closely resembles the head
of a vulture; but the lower mandible can be opened much
wider, so as to form even a straight line with the upper.
The head itself possesses considerable powers of movement,
by means of a short neck. In one zoophyte the head itself
was fixed, but the lower jaw free : in another it was replaced
by a triangular hood, with a beautifully-fitted trap-door,
which evidently answered to the lower mandible. A species
of stony eschara had a structure somewhat similar. In the
greater number of species, each shell was provided with one
head, but in others each had two.
The young cells at the end of the branches necessarily
contained quite immature polypi, yet the vulture-heads
attached to them, though small, were in every respect perfect.
When the polypus was removed by a needle from any
of the cells, these organs did not appear in the least
affected. When one of the latter was cut off from a cell, the
lower mandible retained its power of opening and closing.
Perhaps the most singular part of their structure is, that
when there were more rows of cells than two, both in a Flustra
and an Eschara, the central cells were furnished with these
appendages, of only one-fourth the size of the lateral ones.
Their movements varied according to the species :— in some
I never saw the least motion; while others, with the lower
mandible generally wide open, oscillated backwards and forwards
at the rate of about five seconds each turn; otliers
moved rapidly and by starts. When touched with a needle
the beak generally seized the point so firmly, that the whole
branch might be shaken.
These bodies have no relation whatever with the production
of the gemmules. I could not trace any connexion between
them and the polypus. From their formation being completed
before that of the latter; from the independence of
their movements; from the difference of their size in different
parts of the branch ; I have little doubt that in their
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