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Show 1900.] FROM THE FALKLAND ISLANDS. 523 H. planatus. But Guerin's //. leachii came from the coasts of New Holland, and may therefore quite as well be ovatus as planatus. Miers in 1876 observes that the abdomen of the male is concave, not " deeply notched " on each side as stated in White's description. This criticism certainly applies both to Falkland Islands and Australian forms, and raises a question whether White took his character, not from observation, but from the figure of the pleon in Guerin's ' Iconographie.' White also says that the claws of the last four legs are " considerably curved," which is in correspondence with Guerin's figure and with the term "crochu" applied to them by Guerin in the ' Voy. de la Coquille.' Dana, who is not over-satisfied with White's account of his new genus, describes this claw7 (or tarsus) in H. planatus from Tierra del Fuego as " nearly straight"; and though the difference in this respect between the Patagonian and Australian species is not really very great, yet, the limbs in the latter being more slender, the curvature of the claw is in them more effectively apparent. The massive chelipeds shown in WThite's figure, and alluded to in his generic account, may be those of an old male. They agree pretty well with the claws of Jacquinot's Hymenosoma tridentata, but not with those of Guerin's H. leachii, which are less inflated and very unequal, nor with those figured by Dana, which are small and equal, probably drawn from a female specimen. Whatever may be the Liriopea leachii (Guerin) and Liriopea lucasii, both from Chile and both described by Nicolet, it is not improbable, as already observed, that the Hymenosoma leachii of Guerin is identical with Halicarcinus ovatus Stimpson. Professor Haswell makes them both synonyms of Hymenosoma pAanatum, the separation of Halicarcinus and Hymenicus from Hymenosoma seeming to him to rest " on extremely slight points of distinction " ; and indeed the points are not of imposing magnitude as exhibited in species all of inconsiderable size. But whereas Haswell in 1882 thus unites planatus and ovatus, Miers, who in 1876 had done the same, in 1886 keeps them separate, apparently converted to this view by Tozzetti's work in 1877. For Tozzetti not only makes them separate species,but thinks that there are grounds for allotting planatus to a new genus, overlooking the fact that it is ovatus, as the later species, that would have to change its generic name, if a change were to be made. Tozzetti, after discussing the facial structure in Hymenosoma, continues :-" In a second form the front broad at the base, continued outward by a supra-orbital margin, is inflected below by a distinct and acute tridentate epifrontal fold, produces with the free margin an interantennulary septum which divides the antennarv fossettes on one side and the other, closed further behind and below by a distinct epistome. This form (Halicarcinus planatus, see p. 178) seems to us a new type by the construction indicated. " In the third form the front proceeds straight forward, covering with the base part of the orbital fossette, which has no proper |
