1900.] FKOM *HE FALKLAND ISLANDS. 528 



H. planatus. But Guerin's H. 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 

 Gruerin'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 

 claw (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 effectivel}' apparent. The massive chelipeds shown 

 in White'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 planatum, 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 distiuct and acute tridentate epifroutal 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 



