From many results
of this kind upon which I could report, I select as examples, two, which
were of particular importance to me, and relate to discoveries the great
significance of which in the morphology and classification of the
Crustacea will not be denied even by the opponents of Darwin.
Considerations upon the developmental history of the Crustacea had led
me to the conclusion that, if the higher and lower Crustacea were at all
derivable from common progenitors, the former also must once have passed
through Nauplius-like conditions. Soon afterwards I discovered
Naupliiform larvae of Shrimps ('Archiv fur Naturgeschichte' 1860 1 page
8), and I must admit that this discovery gave me the first decided turn
in Darwin's favour.
(FIGURE 2. Tanais dubius (?) Kr. female, magnified 25 times, showing the
orifice of entrance (x) into the cavity overarched by the carapace, in
which an appendage of the second pair of maxillae (f) plays. On four
feet (i, k, l, m) are the rudiments of the lamellae which subsequently
form the brood-cavity.)
The similar number of segments* occurring in the Crabs and Macrura,
Amphipoda and Isopoda, in which the last seven segments are always
different from the preceding ones in the appendages with which they are
furnished, could only be regarded as an inheritance from the same
ancestors.
(* Like Claus I do not regard the eyes of the Crustacea as limbs, and
therefore admit no ocular segment; on the other hand I count in the
median piece of the tail, to which the character of a segment is often
denied.
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