I 2 I 



assig-ned to Hclice and C/iasinagiiatkiis in the present paper, I prefei: to refer two of Dana's 

 species [subqiiadratiis and granulattis) to Helice and his third species {/aevis) to Paragrapsus. 

 Indeed, in the original description of Helice and Chasmagnat/ms, as conceived by de Haan, 

 the carapace is only little narrowed anteriorly in the former genus, and the postero-lateral 

 margins are subparallel, not distinctly converging backward, and more or less concave; besides, 

 the abdomen of the cf is somewhat narrower, the palm of the chela is higher than long, and 

 the merus of the external maxillipeds, though narrowed towards the ischium, is nearly as 

 broad anteriorly as long. 



The specimen before me is an apparently not full-grown cf and, notwithstanding the 

 brief description of Dana, there are some striking features, that induce me to identify the 

 animal with H. subquadrata. 



The carapace is little vaulted transversely, somewhat more so in a longitudinal direction, 

 notably anteriorly, so that the front is obliquely deflexed. The maximum breadth is lying 

 between the tips of the posterior epibranchial teeth, and the length is 79 — 80°/^ of the greatest 

 breadth, as in de Man's specimens of H. latrcilli. 



The usual areas of the carapace are rather distinct; the epigastric regions are well 

 defined, bulging, separated one from another by a rather • broad medial groove, into which 

 the anterior lobe of the mesogastric regions extends; the cervical furrow is deep at both ends, 

 but interrupted in the middle, so that mesogastric and cardiac region here pass into one 

 another; the latter is smaller and narrower than the former, roughly hexagonal; intestinal 

 region scarcely indicated; hepatic and branchial regions not separated, the latter, as usual, 

 strongly sloping towards the bases of the two last pairs of legs. The whole surface is pitted, 

 the punctae being coarser on the anterior half of the carapace; besides, the epigastric 

 areas and the front present under strong magnification a very minute 

 granulation among the punctae, quite as de Man described in H. latreilli. On 

 the sloping parts of the branchial regions we observe numerous setiferous granules, that 

 tend to arrange themselves in oblique rows; one of these rows is more continuous than the 

 rest and parts from the middle of the postero-lateral margin of the carapace. Quite behind, 

 above the bases of the last two pair of legs, there is on either side of the carapace a 

 conspicuous folding of the surface, that is somewhat sigmoid, but on the 

 whole parallel with the posterior margin; this folding has been observed by 

 DE Man in quite the same way (though in the present species it does not reach so far 

 laterally) in H. latreilli, and, likewise, the distance of both foldings, that are larger than the 

 oblique granulate lines mentioned above, is about equal to the length of each folding. The 

 posterior margin of the carapace is, as usual, accompanied by a fine line, running parallel 

 and very close to it; above the bases of the posterior pair of legs this line more and more 

 approaches the margin and finally disappears altogether. 



In front view the anterior margin of the front turns out to be slightly wavy at either 

 side of the median notch and the lateral angles are more distinct than in the type species of 

 the genus, H. tridens: though the angle is rounded and very obtuse (about 135°), it is at 

 least present, whereas in H. tridens the anterior margin passes without any transition into the 



SIBOGA-EXPEDITIE XXXIXC. 



16 



