104 
THE VOYAGE OF H.M.S. CHALLENGER, 
The latter specimen measures as follows : — 
Adult 3 . 
Lines. 
Millims. 
Length of carapace and rostrum, 
4 
8-5 
Breadth of carapace, .... 
4 
8 - 5 
Length of a chelipede, .... 
. 8i 
18 
Length of first ambulatory leg, . 
5 
10-5 
Subfamily 2. Eumedoniile. 
Eumedoninse , Miers, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 670, 1879. 
Carapace usually rhomboidal or subpentagonal. Rostrum usually bifid or emarginate. 
Depressions separating the regions of the carapace obscure or non-existent. Anterior legs 
of moderate length, chelipedes not trigonous. 
To the genera enumerated in the above cited memoir, Rliabdonotus, A. Milne 
Edwards, is perhaps to be added. 
Ceratocarcinus, Adams and White. 
Ceratocarcinus, Adams and White, Proc. Zool. Soc. Lond., p. 57, 1847; Crust, in Zool. H.M.S. 
“Samarang,” p. 33, 1848. 
„ Miers, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 670, 1879. 
Carapace subhexagonal, about as broad as long, with the dorsal surface moderately 
convex, spinose or tuberculated. The spines of the rostrum are elongated, acute, and 
separated by a rather wide interspace, and there is a well-developed lateral epibranchial 
spine. The orbits are small, circular, excavated below and at the exterior angle, and the 
subocular lobe joins the front, so as completely to exclude the antennae from the orbits. 
The post-abdomen, in the male, is seven-jointed. 
The eyes are small, retractile. The basal (or real second) joint of the antennae is 
slender and occupies the space between the base of the antennules and the inner sub- 
ocular lobe. The exterior maxillipedes are small ; the ischium-joint not produced at its 
antero-internal angle, the merus distally truncated, not produced at the antero-external 
angle, and scarcely emarginate at the antero-internal angle, where the next joint articu- 
lates. The chelipedes are slender and somewhat elongated, with the joints not dilated, 
the merus and carpus sometimes armed with spines ; the dactyli acute, shorter than the 
palms and dentated on the inner margins ; the ambulatory legs are slender, with the 
joints not dilated, the merus sometimes armed with a distal spine ; the dactyli nearly 
straight. 
