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Updated: September 28, 2025
Once more, the prevalence of Macrurous before Brachyurous Podophthalmia is, apparently, a fair piece of evidence in favour of progressive modification in the same order of Crustacea; and yet the case will not stand much sifting, seeing that the Macrurous Podophthalmia depart as far in one direction from the common type of Podophthalmia, or from any embryonic condition of the Brachyura, as the Brachyura do in the other; and that the middle terms between Macrura and Brachyura the Anomura are little better represented in the older Mesozoic rocks than the Brachyura are.
Consequently we may apparently assume, without hesitation, that when the Brachyura and Macrura separated, the primitive ancestors of each of these groups passed through a more complete metamorphosis, and that the transition to the present mode of development belongs to a later period.
Once more, the prevalence of Macrurous before Brachyurous Podophthalmia is, apparently, a fair piece of evidence in favour of progressive modification in the same order of Crustacea; and yet the case will not stand much sifting, seeing that the Macrurous Podophthalmia depart as far in one direction from the common type of Podophthalmia, or from any embryonic condition of the Brachyura, as the Brachyura do in the other; and that the middle terms between Macrura and Brachyura the Anomura are little better represented in the older Mesozoic rocks than the Brachyura are.
We may hope to obtain the most striking examples in the still unknown developmental history of the various Schizopoda, Peneidae, and, indeed, of the Macrura in general. At present the multifarious Zoea-forms appear to be particularly instructive.
There is one specimen in the Museum, a young bird of the year. ARCTIC TERN. Sterna macrura, Naumann. French, "Hirondelle de mer arctique."
Smith interpreted the alteration in the male as a development of female secondary characters, but it is obvious from the condition in Macrura or tailed Decapods, like the lobster or crayfish, that the abdomen or tail of the male originally carried appendages similar to those of the female, and that the male character is a loss of these appendages.
Conseil used the methods of our mentor Professor Milne-Edwards, who puts the decapods in three divisions: Brachyura, Macrura, and Anomura. These names may look a tad fierce, but they're accurate and appropriate.
The ANNULOSA. The Carboniferous Insecta and Arachnida are neither less specialized, nor more embryonic, than those that now live, nor are the Liassic Cirripedia and Macrura; while several of the Brachyura, which appear in the Chalk, belong to existing genera; and none exhibit either an intermediate, or an embryonic, character.
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.
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