It would follow:--
1. From the structure of the clasp-forceps: that M. exilii, etc. and M.
Fresnelii would branch off together from a stem which branches off from
M. palmata.
2. From the presence or absence of the secondary flagellum: that M.
palmata, etc. and M. exilii, etc. would branch off together from a stem
which branches off from M. Fresnelii.
As, in the first case, among the Crabs, a typical agreement of
arrangements produced independently of each other would have been a very
suspicious circumstance for Darwin's theory, so also, in the second,
would any difference more profound than that of very nearly allied
species. Now it seems to me that the secondary flagellum can by no means
furnish a reason for doubting the close relationship of M. Fresnelii to
M. exilii, etc., which is indicated by the peculiar structure of the
unpaired clasp-forceps. In the first place we must consider the
possibility that the secondary flagellum, which is not always easy to
detect, may only have been overlooked by Savigny, as indeed Spence Bate
supposes to have been the case. If it is really deficient it must be
remarked that I have found it in species of the genera Leucothoe,
Cyrtophium and Amphilochus, in which genera it was missed by Savigny,
Dana and Spence Bate--that a species proved by the form of the Epimera
(Coxae Sp. B.) of the caudal feet (uropoda Westw.
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