248 
THE VOYAGE OF H.M.S. CHALLENGER. 
In all these specimens the chelipedes are of moderate length, not greatly elongated, 
as in the large Australian males, the types of the species, in the British (Natural 
History) Museum ; the front, in the females especially, is somewhat broader, and the 
chelipedes relatively much shorter, with the merus-joints angulated, and armed with two 
or three spinules on the anterior margin, near the distal extremity, besides the spinule 
on the middle of the posterior margin, which is found also in the large adult males. 
These differences will perhaps be found to be of specific importance. 
The largest female measures as follows : — 
Adult ?. 
Lines. 
Millims. 
Length of carapace, ....... 
5 
10-5 
Breadth to base of antero-lateral spine, ... 
9 
19 
Length of a clielipede, ...... 
10 
21 
Macrophthalminse. 
Macrophthalmus, Latreille. 
Macrophthalmus, Latreille, in Cuvier, Regne Animal, ed. 2, vol. iv. p. 44, 1829. 
„ Milne Edwards, Hist. Nat. Crust., vol. ii. p. 63, 1837; Ann. d. Sci. Nat., 
ser. 3, Zool. xviii. p. 155, 1852. 
Carapace usually quadrate, depressed and broadly transverse, with the cervical and 
cardiaco-branchial sutures distinct on the lateral margins, nearly straight, and armed with 
one or more teeth behind that at the exterior angle of the orbit ; front very narrow and 
deflexed, so as in great measure to conceal the antennules, and distally truncated. The 
orbits are very large and occupy the whole width of the anterior face of the carapace, 
between its antero-lateral angles and the front, and they are not defined externally, 
beneath the antero-lateral or exterior orbital angle. The epistoma is very narrow, 
usually linear-transverse. The longitudinal ridges of the endostome or palate are either 
absent or very obscurely indicated. The post-abdomen (in the male) is distinctly seven- 
jointed, and does not occupy the whole width of the sternum, between the bases of the 
fifth ambulatory legs. The ocular pedicels are slender and considerably elongated, and 
in certain species are even prolonged laterally beyond the exterior angle of the orbit. 
The [antennules are transversely plicated. The antennae are not excluded from the 
orbital hiatus, their basal portion is very short ; the basal joint is usually transverse 
and does not nearly reach the frontal margin ; the flagellum is somewhat elongated. 
The exterior maxillipedes do not meet along their inner margins ; the ischium and 
merus-joints of the endognathi are distally truncated, or their anterior margins are even 
slightly concave ; the carpus is articulated with the merus at its antero-external angle. 
The chelipedes (in the adult males) are usually subequal and somewhat elongated, with 
the merus trigonous ; carpus without or with only a small spine on the interior margin ; 
palm elongated, compressed, and rounded or subcarinated on the superior margin ; 
fingers compressed and minutely denticulated on the interior margins, and usually 
