It was found to be
of this structure by La Valette in Niphargus (Gammarus puteanus), and by
Claus in Phronima; and I have found it to be the same in a considerable
number of species belonging to the most different families.* (* The
young animals in the egg, a little before their exclusion, are usually
particularly convenient for the observation of the fissures in the
heart; they are generally sufficiently transparent, the movements of the
heart are less violent than at a later period, and they lie still even
without the pressure of a glass cover. Considering the common opinion as
to the distribution of the Amphipoda, namely, that they increase in
multiplicity towards the poles, and diminish towards the equator, it may
seem strange that I speak of a considerable number of species on a
subtropical coast. I therefore remark that in a few months and without
examining any depths inaccessible from the shore, I obtained 38
different species, of which 34 are new, which, with the previously known
species (principally described by Dana) gives 60 Brazilian Amphipoda,
whilst Kroyer in his 'Gronlands Amfipoder' was acquainted with only 28
species, including 2 Laemodipoda, from the Arctic Seas, although these
had been investigated by a far greater number of Naturalists.)
The sole unimportant exception which I have hitherto met with is
presented by the genus Brachyscelus,* (*According to Milne-Edwards'
arrangement the females of this genus would belong to the "Hyperines
ordinaires" and the previously unknown males to the "Hyperines
anormales," the distinguishing character of which, namely the curiously
zigzagged inferior antennae, is only a sexual peculiarity of the male
animals.
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