36 
THE VOYAGE OF H.M.S. CHALLENGER. 
intermediate between the two varieties of this sex figured by De Haan, having the 
rostrum slender and elongated as in the one, and the antero -lateral lobes of the carapace 
obsolete as in the other form. In the females, the rounded antero-lateral lobes scarcely 
exceed in width the obliquely truncated postero-lateral lobes of the carapace. 
The largest male and female have the following dimensions : — 
Adult $ . 
Lines. 
Millims. 
Length of carapace and rostrum, .... 
14 
29-5 
Breadth of carapace, including the epibranchial lobes, 
8* 
18 
Length of chelipede, ..... 
14| 
30*5 
Length of first ambulatory leg, .... 
181 
39 
Adult $. 
Length of carapace and rostrum, .... 
10 
21-5 
Breadth of carapace at the lateral epibranchial lobes, 
n 
15-5 
Length of chelipede, ..... 
n 
15-5 
Length of first ambulatory leg, .... 
Hi 
24 
Another small male example (with all the legs deficient) was obtained in the 
-Arafura Sea (depth and other particulars not stated) ; the dorsal surface of the carapace 
is flat and nearly smooth ; the rostrum, in a dorsal view, short and triangulate, the 
antero-lateral lobes of the carapace wholly obsolete, and the postero-lateral lobes small 
and acute. 
Adult <$ . Lines. Millims. 
Length of carapace and rostrum, . . . . . 5 10 '5 
Breadth of carapace, nearly ...... 3 6 
Menaethius, Milne Edwards. 
Menxthius, Milne Edwards, Hist. Nat. Crust., vol. i. p. 338, 1834. 
„ Miers, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 649, 1879. 
Carapace subpyriform, moderately convex, and tuberculated on the dorsal surface, 
with a large triangulate prseocular spine, but no postocular spine. Eostrum simple, 
slender, acute, or emarginate at apex. Post-abdomen in the male seven-jointed, in the 
female usually five-jointed, 'the penultimate joint formed by the coalescence of three 
segments. Eyes small, mobile, but not perfectly retractile. Basal antennal joint slightly 
wider at the base than at the distal extremity, which is unarmed ; flagellum exposed 
and visible from above at the side of the rostrum. Merus of the exterior maxillipedes 
truncated at the distal extremity and with a prominent antero-external angle, and slightly 
notched at the antero-internal angle, where it is articulated with the next joint. Cheli- 
pedes (in the male) well developed; with the palm slightly compressed ; fingers acute, and 
having between them, when closed, an interspace at the base. Ambulatory legs of 
moderate length ; the joints subcylindrical', not dilated or compressed ; dactyli slightly 
curved and partially retractile. 
