1 86 

 Ommatocarcinus White. 



1852. Ommatocarcinus White. Append, in Stanley's Voy. H. M. S. "Rattlesnake", v. 2, p. 393. 



There can be no doubt, as has been suggested by Miers, that this genus is nearly 

 related to Goneplax, which it resembles in the great elongation of the eye-stalks and the 

 chelipeds, the bulging of the corneae, the narrowness of the front and the fine build of the 

 dactyli of the walking legs. 



From Goneplax the present genus is distinguished by the greatly-developed, spiniform 

 external orbital angle being directed straightly outward, by the much concave lateral margins, 

 and consequently the acuminate angles, of the front, and by the shortness of the antennae. 



Two species have been described from Australian and New Zealandian waters, viz.: 

 O. t7tacgillivrayi White ^) and O. hnttoni Filhol "). I shall not venture to give a diagnostic key 

 to these species (which are both incompletely known), because I had no opportunity of consulting 

 the original description and figure of White. It is most remarkable, that apparendy a new 

 species of the genus has been found by the "Siboga" in the Indo-Malayan Archipelago. 



I. Ommatocarcinus orientalis n. sp. PI. 10, Fig. 2. 



Stat. 260. 5°36'.5 S., I32°55'.2E. North-west of Kei Islands. Depth 90 m. i cT. 



This remarkable species is somewhat vaulted in transverse direction, more so in a 

 longitudinal sense; regions are very faintly indicated on the carapace, but there is a trace of 

 two epigastric lobes, a longitudinal, broad and shallow depression behind them on the gastric 

 region, and branchial and hepatic regions are separated by a concave groove on either side, 

 much curving backward on the median side, but not connected by a cervical groove, that is 

 entirely absent. The whole surface is perfectly smooth, without any granules or hairs. 



The front is obliquely deflexed, somewhat constricted between the eye-stalks 

 (fig. 2b)\ measured in dorsal view it is little less than one-fourth the greatest width of the 

 carapace, the anterior margin is somewhat concave, with an obtuse prominence in the middle, 

 and the lateral angles are acuminate, not rectangular. The supra-orbital margins are 

 greatly sloping backward, so that a line connecting the external orbital angles divides 

 the median longitudinal axis of the carapace into two nearly equal parts; (in O. hiittotii, and 

 probably also in White's species, the supra-orbital margins are nearly transverse), in the middle 

 third of their course they are bulging forward, becoming again concave towards the spiniform 

 external orbital angles, which are large, directed straightly outward, like in the other 

 species, not flattened; the distance between the tips of these teeth is only slightly less than 

 twice the length of the carapace. The lateral margins of the latter are unarmed, straight, greatly 

 converging backward, so that the breadth of the carapace at the level of the penultimate pair 

 of legs measures not yet two-thirds of its greatest breadth, the po!?terior margin is perfectly straight. 



1) L. c, p. 393, pi. 5, f. i; O. macgilliviri H. Milne-Edwards, Ann. Sc. Nat. (3), t. 18, 1S52, p. 163; 0. macgillhrayi Wiers, 

 Kep. "Challenger", Brachyura, 1886, p. 247. Hab. Port Curtis (Australia) and Queen Charlotte Sound near Long Island (New Zealand). 



2) Miss, lie Campbell, t. 3, prt 2, 1885, p. 384, pi. 43, f. 1—2, 5. Hab. Otago (New Zealand). 



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