REPORT ON THE BRACHYURA. 
247 
endostome is without distinct longitudinal ridges ; these are only very faintly indicated 
in their basal portion. The post-abdomen in the male is distinctly seven-jointed and 
resembles that of Gonoplax, but is distally rather broader ; as in that genus, the two 
basal segments occupy the whole of the interspace between the bases of the ambulatory 
legs. The eye-pedicels are slender and greatly elongated, reaching the extremities of 
the antero-lateral angles of the carapace or even prolonged slightly beyond them. The 
antennules are transversely plicated. The antennae occupy the narrow interior hiatus of 
the orbits; the basal joints are very short and do not nearly reach the lateral angles of 
the front ; the flagella are moderately elongated. The ischium-joint of the exterior 
maxiflipedes is not produced at its antero-internal angle ; the merus is short, distally 
truncated, with the antero-external angles rounded. The chelipedes (in the adult males) 
are subequal and very greatly developed, sometimes exceeding in length three and a half 
times the greatest width of the carapace ; the merus is subcylindrical and projects far 
beyond the antero-lateral angles of the carapace ; the carpus is short and unarmed ; 
palm slightly compressed, and nearly as long as the merus ; fingers enclosing a wide 
basal interspace, compressed, distally acute, and irregularly dentated on the anterior 
margins. The ambulatory legs are elongated and compressed, without spines, and the 
dactyli are styliform and about as long as the penultimate joints. 
Perhaps the nearest ally of this genus is Gonoplax, which Ommatocarcinus resembles 
in general form, in the great development of the chelipedes, in that the abdomen covers 
the whole width of the sternum at the base, and especially in the articulation of the fourth 
joint of the exterior maxillipedes with the merus at or near the antero-internal angle of 
the latter joint. Ommatocarcinus is distinguished from Gonoplax by the narrower 
front, the greater development of the eye-peduncles, and the greatly developed antero- 
lateral spine of the carapace. 
I believe the only described species of this genus is the following : — 
Ommatocarcinus macgillivrayi, White. 
Ommatocarcinus macgillivrayi, White, Append, in Stanley, Yoy. of the “Rattlesnake,” vol. ii. 
p. 393, pi. v. fig. 1, 1852. 
„ „ Milne Edwards, Ann. d. Sci. Nat., ser. 3, Zool., vol. xviii. p. 163, 
1852. 
Queen Charlotte Sound, near Long Island, New Zealand, 10 fathoms, Station 167a 
(a young male and two small but ova-bearing females). 
The smallest female has the following dimensions : — 
5 . Lines. 
Length of carapace, a little over ..... 4 
Breadth of carapace (to base of the spines at the antero-lateral angles), . 7 
Millims. 
9 
15 
