242 COLLECTIONS FKOM MELANESIA. 



86. Pseudorhombila sulcatifrons (Stimpson), var. australiensis. 



(Plate XXIV. fig. C.) 



As this variety may prove to be specifically distinct, I subjoin the 

 following description : — 



As in Heteroplax dentata, Stimpson, the carapace is slightly trans- 

 verse, anteriorly somewhat detlexed, posteriorly plane ; it attains its 

 greatest width at the third lateral tooth. The front is about half 

 the width of the carapace ; its anterior margin is faintly transversely 

 sulcated, without any median fissure, and is straight ; there is, how- 

 ever, a small notch on each side close to the lateral angles, which 

 thus are separated as small teeth. The antero-lateral margins of 

 the carapace are much shorter than the postero-lateral and armed 

 with four teeth (the outer orbital angle included) ; the third tooth 

 is larger and more prominent than the others, the fourth the 

 smallest ; there is a small median notch in the middle of the upper 

 orbital margin ; slight transverse inequalities are apparent on the 

 front of the gastric region and on the sides of the carapace near the 

 lateral teeth. The postabdomen is triangulate, with the segments 

 distinct, the penultimate and the last being the longest ; the second 

 segment covers the whole width of the sternum and reaches to the 

 bases of the fifth legs. The eyes are placed upon rather short thick 

 pedicels. The antennules are rather long and transversely folded. 

 The basal antennal joint is slender, and although longer than either 

 of the following joints, does not reach to the frontal margin ; the 

 flagellum is elongated. Scarcely any traces are visible of palatal 

 ridges. The merus-joint of the maxillipedes is quadrate, and much 

 shorter than the preceding ; the next joint is articulated with it at 

 its antero-internal angle. The chelipedes are of nearly equal size ; 

 merus trigonous, short, with a tooth near the distal end of its upper 

 margin ; carpus smooth externally, with a spiniform tooth on its 

 inner margin ; palm smooth externally, moderately convex ; fingers 

 about as long as the palm, denticulated on their inner margins and 

 having between them scarcely any interspace when closed. Ambu- 

 latory legs rather long, with the joints very slender, unarmed ; the 

 last three with their margins somewhat scantily pubescent. Length 

 of carapace nearly 3 lines (6 millim.), breadth nearly 4 lines 

 (8 millim.) ; length of ambulatory leg of third pair about 6| lines 

 (14 millim.). 



The single specimen was obtained at Port Molle, 14fms. (Xo. 93), 

 and is apparently a female, although possessing an unusually nar- 

 row postabdomen. It differs from Heteroj<l<t.r dentata and H. trans- 

 versa, Stimpson*, in having the second tooth of the antero-lateral 

 margins as long as the preceding, and also, it would appear, the 

 shorter thicker eye-peduncles, and from the latter also in the 

 narrower carapace. From the typical P. sulcatifrons (Stimpson), 

 from Hong-Kong, it is distinguished only by the non-emarginate 



* Proc. Acad. Nat. Sci. Philad. p. 94 (1858). 



