Journal of the Proceedings of the Linnean Society - Vol. 3 / Zoology

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On the Importance of an Examination of the Structure of the Integument of Crustacea in the determination of doubtful Species.—Application to the genus Galathea , with the Description of a New Species of that Genus. By Spence Bate, Esq., F.L.S.
Of the various genera of Decapod Crustacea none are more interesting, or more difficult of description, than those which constitute the family Galatheadæ.
The interest attaching to these forms arises from the intermediate position which they occupy in the natural arrangement of the class, their structure placing them between the Macrura and Brachyura; in accordance with which we find that, whilst Professor M.-Edwards classes them among the Macrura, Professor Bell, in his work on the British Crustacea, places them (more correctly, as we think) in the intermediate group of Anomura.
This opinion is fully borne out both in the development of the animals and in their structure in the adult state.
The early form of the larva bears, anteriorly, a resemblance to the Brachyural type, whilst the caudal appendages assimilate to those of the Macrura. The same conditions obtain in the young of Anomura. At the time of birth, the larva, like that of the Brachyura, has only the two gnathopoda developed, whilst the termination of the tail is like that of a fish, as in the Macrura. In the adult, the internal antennæ possess short flagella and complementary appendages, such as exist in the order Brachyura, whilst the external antennæ have the long and slender flagella proper to the Macrura. The scale , however, commonly appended to the external antennæ in the latter order is wanting, a circumstance which exhibits a relation to the Brachyura.
An examination of the legs shows that the coxæ are fused with the thorax, as in the Brachyura, and not articulated with it as in the Macrura, whilst, on the other hand, the posterior division and caudal termination approach the Macrural type more nearly than that of the Brachyura, the animal thus assuming a character intermediate between the two orders.