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The orbits are long, narrow trenches, for the reception of the eye-peduncles ; the inferior 

 margin (fig. 2a), which, Hke the opposite one, is wavy, presents a broad, triangular, hut low tooth 

 in its inner part, tipped by a feathered hair; similar hairs, three in number, are placed on the 

 convex part of the margin. Both margins are very finely crenulate, the inferior one does not project 

 beyond the superior, in dorsal view, and on the dorsal roof of the orbit is placed a serial row 

 of ordinary hairs, increasing in length towards the outer tooth. The eye-stalks are very 

 m u c h e I o n g a t e , the basal joint is not very thick, but the second greatly enlarges gradually 

 towards the much bulging cornea, which in dorsal view occupies one-third of the whole length 

 of the eye-stalk ; the length of the latter e.xceeds the breadth of the orbit, so that the stalk, 

 if laid back into the orbit, slightly projects with the terminal part of the cornea beyond the 

 outer orbital angle. 



The antennulae are folded quite transversely beneath the anterior margin of the front ; 

 they are much longer and thicker than the small antennae, the peduncle of which rises freely 

 at the inner side of the base of the inner suborbital lobe, in the wide gap between this lobe 

 and the lateral angle of the front; the flagellum of the antennae consists of about seven joints, 

 which together are scarcely as long as one-third of the length of the eye-peduncle. Epistome 

 distinct, somewhat produced at its free margin, nearly vertical. Margins of buccal cavity con- 

 vergent backward. External maxillipeds (fig. 2 r) greatly divergent forward, ischium longer than 

 broad and longer than the small, quadrate merus, the antero-external angle of which is not 

 produced and rounded off (according to Filhol's figure 5 this angle is greatly obtuse); exognath 

 half as broad as ischium ; inner margin of ischium and merus crenulate and hairy. 



The chelipeds are greatly elongate, as seems to be the usual case in the genus, at least 

 in the (ƒ, measuring more than 3 times the length of the carapace-, in my specimen they are 

 equal in length and size (in O. Jntttoni the right cheliped of the 9, the only sex known, is 

 slightly the larger). Meropodite (fig. 2d) long-stretched, nearly cylindrical in section, but inner 

 margin with a thin, sharp keel, that is abruptly cut off near the distal articulation and regularly 

 crenulate and somewhat hairy for the greater part of its length, upper border wholly unarmed 

 (both in O. inacgillivrayi and O. Iiuttoni it is armed with a spinule in the middle, and in the 

 9 of the first species there are 2 — 3 spinules on the distal part of the anterior border, according 

 to Miers). Wrist very small ; in dorsal view of the cheliped the inner angle is very inconspicuous, 

 but if the cheliped be outstretched and examined in outer view (fig. 2d) this inner angle turns out to 

 be large, triangular, and directed upward. Chela elongate, palm twice as long as high, gradually 

 increasing in height towards base of movable finger, borders rounded ; near upper border the 

 palm is very minutely granulate, but not hairy; the outer surface, like that of the whole cheliped, 

 bears some few low granules or meandrian wrinkles; the fingers are greatly shorter than the 

 palm, depressed, but not keeled ; the fixed finger is straight, in a line with the under border 

 of the palm, slighth>- curved up at the tip, and regularly crenulate at inner margin; the movable 

 finger is rather high, curved in its distal half, inner margin with a few indistinct crenulations, 

 the basal one of which, in the right chela, is much the largest. 



Ambulatory legs slender, but not very long, shorter and weaker than the chelipeds, but 

 more slender than in O. huttoni, according to Filhol's figure; they are wholly hairless, even 



39 



