92 A HISTORY OF RECENT CRUSTACEA 
rhomboides (Linn.), called in Bell’s ‘History of the 
British Crustacea’ Gonoplax angulata (Fabricius), the 
angular crab, the specific name obviously, and the generic 
name probably, alluding to the angular character of the 
carapace. A second species, closely resembling the first, 
and named Gonoplax sinuatifrons, Miers, was obtained by 
the Challenger at Amboina. The elongated orbits and 
eye-stalks cannot fail to attract attention, and the latter 
especially when they are suddenly erected from a position 
of rest within the former. The male has the chelipeds of 
a remarkable length, and these, at least’ when in confine- 
ment, he is fond of clashing together in a noisy and 
perhaps threatening manner. The joints of these limbs 
are so proportioned that while they are able to seize food 
at a great distance, they can also convey it to the mouth. 
The pleon is seven-jointed in both sexes. 
Ommatocarcinus, White, 1852, is distinguished from 
its near neighbour Gonoplax by a still narrower ‘front,’ a 
great development of the antero-lateral spine on each side 
of the carapace, and still more elongate eye-stalks, to 
which reference is made in the generic name, meaning 
‘the crab with the eyes.’ There is but one species, Omma- 
tocarcinus Macqillivrayi, White. This is found in Austra- 
lan and New Zealand waters. 
Macrophthalmus, Latreille, 1829, with a name mean- 
ing ‘long-eye, surpasses the two preceding genera in the 
length of the orbits, and the eye-stalks are exorbitant in 
the literal sense in certain species, in which they are pro- 
longed laterally beyond the orbit’s outer angle. The 
species are numerous, occurring ‘in the littoral or shallow 
waters of all parts of the Indo-Pacific region.’ In some of 
the species, as also in the genera Helice, de Haan, 1835, 
and Metaplax, Milne-Edwards, 1852, the males have on 
the arms of the chelipeds a short horny ridge, which Dr. 
de Man calls ‘the musical crest,’ on the supposition that 
the crab produces musical sounds by rubbing this crest 
against a row of granules below the orbit. Naturally 
this crab-music must only be judged by a crustacean 
standard. 
