ll-developed olfactory organs, through the movement of
its long, flexible body, furnished with muscles, and with the mouth
seated on the summit. We have already seen one instance of a Cirripede,
the Anelasma, obtaining its food without the aid of cirri, by means of
its probosciformed, flexible mouth. The eye can serve only to announce
to the male when the female opens her valves, allowing occasionally some
minute prey to enter. In ordinary Cirripedes the penis is long,
articulated, and capable of varied movements, I presume for the purpose
of impregnating each separate ovum: the male Ibla has no such organ; and
no doubt the whole body, furnished like the penis with longitudinal and
transverse muscles, serves the same purpose! I may remark, that it seems
surprising that so small a male should secrete sufficient semen to
impregnate the ova of the female, but the ova are not nearly so numerous
in Ibla as in most genera of Cirripedes; and the smallness of the males
in some parasitic Crustacea has already been alluded to. The male must
always be younger than the female, for the latter must first grow large
enough for the larva of the male to crawl into her sack. Whether the
male lives as long as the female I know not, but he certainly lives for
a considerable period and increases in size, as shown by the depth to
which the end of the peduncle is imbedded. Moreover we shall see, under
the next species, that the male is metamorphosed from a larva, not one
sixth of its own size.

In the male Ibla, abortion has been carried to an extraordinary and, I
should think, almost unparalleled extent. Of the twenty-one segments
believed to be normally present in every Crustacean, or of the seventeen
known to be present in Cirripedes, the three anterior segments are here
well developed, forming the peduncle: the mouth consists as usual of
three small segments: the succeeding eight segments are represented by
the rudimentary and functionless thorax, supporting only two pair of
distorted, rudimentary and functionless cirri: the seven segments of the
abdomen have disappeared, with the exception of the excessively minute
caudal appendages; so that, of the twenty-one normal segments, fifteen
are more or less aborted. The state of the cirri is curious, and may be
compared to that of the anthers in a semi-double flower; for they are
not simply rudimentary in size and function, but they are monstrous, and
generally do not even correspond on opposit