EEPOET ON THE BEACHYUEA. 
201 
Portunus corrugatus is now for the first time. I believe, recorded from the southern 
hemisphere ; its occurrence in the Japanese Seas was noted by de Haan so long ago as 
1835, and again by Dr. Stimpson in 1858 (as Portunus strigilis), and by myself in 
1876. The form designated by A. Milne Edwards Portunus sub corrugatus, from the 
Eed Sea, is probably, as I have already noted, a variety of Portunus corrugatus. 
Platyonychus, Latreille. 
Platyonychus, Latreille (pt.), Nouv. Diet. d. Hist. Nat., vol. xxvii. p. 4, 1818. 
,, Milne Edwards, Hist. Nat. Crust., vol. i. p. 435, 1834. 
„ A. Milne Edwards (pt.), Archiv. Mus. Hist. Nat., voL x. p. 410, 1861. 
Anisojous, de Haan (subgen.), Crust, in v. Siebold, Fauna Japonica, p. 12, 1833. 
Carapace depressed and transverse ; the dorsal surface without tubercles or trans- 
verse ridges ; the front is rather narrow, and armed with three or four lobes or teeth ; 
the antero-lateral margins arcuated, and armed with five teeth or spines, including the 
lobe at the exterior orbital angle and the lateral epibranchial tooth, which is no longer 
than the preceding tooth ; the orbits are rather widely open above, and have one or two 
fissures in the superior, and one in the inferior margin. The ridges of the endostome 
are obsolete. The post-abdomen is usually distinctly seven-jointed, but in Platyonychus 
ocellatus it is five-jointed, with the third to the fifth segments consolidated. The eyes 
are of moderate length. The basal joint of the antennae is short and not dilated, and 
occupies, but does not wholly fill, the interior hiatus of the orbit, and is not united at its 
distal extremity with the front. The exterior maxillipedes are rather large ; their 
ischium joint is not produced at the antero-internal angle ; the merus is obliquely 
truncated at the distal extremity, with the antero-external angle rounded and not at all 
produced. The chelipedes (in the adult males) are subequal and not greatly elongated, 
with the palms externally more or less distinctly longitudinally costatecl ; the fingers 
elongated, and armed on the interior margins with large, triangular lobes, alternating 
with smaller teeth. The ambulatory legs are of moderate length, with the dactyli 
styhform and compressed ; the fifth or natatory legs have, as usual, the penultimate and 
terminal joints compressed and dilated ; the terminal joint not lanceolate as in 
Portumnus, but broadly ovate and rounded at the distal extremity. 
I have elsewhere 1 proposed to restrict this genus to the forms with broader carapace 
and more broadly dilated and ovate dactyli of the fifth or natatory legs, and to separate, 
under Leach’s designation Portumnus, the other species included by A. Milne Edwards 
in Platyonychus. Thus restricted, the genus Platyonychus will include the following 
species, the first two of which are, I believe, confined to shallow water : — 
1 Crust, in Zool. H.M.SS. “Erebus” and “Terror,” p. 2, 1874. 
(ZOOL. CHALL. EXP. — PART XLIX. 1886.) 
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