250 
THE VOYAGE OF H.M.S. CHALLENGER. 
and the transverse sulci of the carapace are not more deeply indicated than in that 
species. The ambulatory legs are relatively more elongated and very slender (one only 
remains perfect, and is detached in this specimen). Its dimensions are as follows : — 
Young 9 . Lines. Millims. 
Length of carapace, nearly ...... 2 4 
Breadth of carapace, . . . . . . . 2£ 5 '5 
Macrophthalmus serratus, Adams and White (PI. XX. fig. 1). 
Macrophthalmus serratus , Adams and White, Crust, in Zool. H.M.S. “Samarang,” p. 51, 
1848. 
„ ,, Milne Edwards, Ann. d. Sci. Nat., ser. 3, ZooL, vol. xviii. p. 159, 1852. 
Japan, Kobe, 8 to 10 fathoms (a small male and female). 
These specimens are referred with much doubt to this species, on account of their 
very small size. One of the chelipedes in the male is deficient. The carapace is more 
finely granulated than in adult examples of Macrophthalmus serratus, the front perhaps 
somewhat broader, and the antero-teeth much less prominent. As in adult specimens 
there are obscure indications of a fourth lateral marginal tooth. In the female the first 
lateral tooth is less prominent than the following. I have observed a similar variation 
in adult males. 
The figure of the adult is from a male of large size in the collection of the British 
(Natural History) Museum. In an adult female, also from the Philippines, in the 
collection, the antero-lateral teeth are less prominent, and the small Challenger 
specimens in these particulars more nearly approach this example. 
Hemiplax, Heller. 
Hemiplax, Heller, Crust, in Reise der “Novara,” p. 40, 1865. 
,, Miers, Cat. New Zeal. Crust., p. 33, 1876. 
This genus was established by Dr. Heller for a species very nearly afiied to Macroph- 
thalmus, but differing from the typical species of that genus in the less transverse 
carapace and broader front, which is at least one-third of the width of the carapace at 
the antero-lateral angles. In all other characters it nearly resembles Macrophthalmus. 
As in that genus the exterior maxilliped.es do not meet along the inner margins, and 
their merus-joints are short, distally truncated, and are not, as in Metaplax (to which 
Hemiplax is also very nearly related), traversed externally by an oblique piliferous crest. 
The chelipedes (as in Macrophthalmus) are subequal, and shorter than the ambulatory 
legs, and the fingers are finely denticulated on the inner margins. 
