Report on the zoological collections made in the Indo-Pacific Ocean ...

—242 COLLECTIONS FKOM MELANESIA.86. PseudorhomMa sulcatifrons (Stimiyson), var. australiensis.(Plate XXIV. fig. C.)As this variety may prove to be specifically distinct, I subjoin thefollowing description :As in Heteroplax dentata, Stimpson, the carapace is slightly transverse,anteriorly somewhat deflexed, posteriorly plane ; it attains itsgreatest width at the third lateral tooth. The front is about halfthe width of the carapace ; its anterior margin is faintly transverselysulcated, without any median fissure, and is straight ; there is, however,a small notch on each side close to the lateral angles, whichthus are separated as small teeth. The antero-lateral margins ofthe carapace are much shorter than the postero-lateral and armedwith four teeth (the outer orbital angle included) ; the third toothis larger and more prominent than the others, the fourth the.smallest ; there is a small median notch in the middle of the upperorbital margin ; slight transverse inequalities are apparent on thefront of the gastric region and on the sides of the carapace near thelateral teeth. The postabdomen is triangulate, with the segmentsdistinct, the penultimate and the last being the longest ; the secondsegment covers the whole width of the sternum and reaches to thebases of the fifth legs. The eyes are placed upon rather short thickpedicels. The antennules are rather long and transversely folded.The basal antennal joint is slender, and although longer than eitherof the following joints, does not reach to the frontal margin ; theflagellum is elongated. Scarcely any traces are visible of palatalridges. The merus-joint of the maxillipedes is quadrate, and muchshorter than the preceding ; the next joint is articulated wdth it atits antero-internal angle. The chelipedes are of nearly equal size ;merus trigonous, short, with a tooth near the distal end of its uppermargin ; carpus smooth externally, with a spiniform tooth on itsinner margin ;palm smooth externally, moderately convex ; fingersabout as long as the palm, denticulated on their inner margins andhaving between them scarcely any interspace when closed.Ambulatorylegs rather long, with the joints very slender, unarmed ; thelast three with their margins somewhat scantily pubescent. Lengthof 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, 14 fms. (No. 93),and is apparently a female, although possessing an unusually, narrowpostabdomen. It difters from Heteroplcuv dentata and H. transversa,Stimpson*, in having the second tooth of the antero-lateralmargins as long as the preceding, and also, it would appear, theshorter thicker eye-peduncles, and from the latter also in thenarrower carapace. Prom the typical P. sulcatifrons (Stimpson),from Hong-Kong, it is distinguished only by the non-emarginate* Proc. Acad. Nat. Sci. Philad. p. 94 (1858).