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Updated: May 5, 2025
It would follow: 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. 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.
Melita exilii n. sp., male, enlarged five times. A second example. This want of symmetry is something so unusual among the Amphipoda, and the structure of the clasp-forceps differs so much from what is seen elsewhere in this order, and agrees so closely in the five species, that one must unhesitatingly regard them as having sprung from common ancestors belonging to them alone among known species.
Now, if the presence or absence of the secondary flagellum possessed the significance of a distinctive generic character, which is usually ascribed to it, or if there were other important differences between Melita Fresnelii and the other species above-mentioned, which would make it seem natural to separate M. Fresnelii as a distinct genus, and to leave the others united with the rest of the species of Melita that is to say, in the sense of the Darwinian theory, if we assume that all the other Melitae possessed common ancestors, which were not at the same time the ancestors of M. Fresnelii this would stand in contradiction to the conclusion, derived from the structure of the clasp-forceps, that M. Fresnelii and the four other species above-mentioned possessed common ancestors, which were not also the ancestors of the remaining species of Melita.
As the males of several species of Melita are distinguished by the powerful unpaired clasp-forceps, the females of some other species of the same genus are equally distinguished from all other Amphipoda by the circumstance that in them a peculiar apparatus is developed which facilitates their being held by the male.
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.
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