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

268 COllECTIONS FKOM MELANESIA.From most of its congeners tliis species is distinguished by theabsence of a distinct rostrum, and the form and armature of thelarger chelipede ; the latter character will distinguish it from E.tricarinahis and E. acantholejpis, Stimpson, from Japan and PortJackson, species in which the rostrum is absent. From the foregoingspecies it is at once distinguished by the longer, slenderereye-peduncles with shorter basal scales, the form of the chelae,slenderer ambulatory legs, &c.11. Petrolisthes japonicus {De Haan), var. inermis, Haswell.Port MoUe (No. 103), several specimens obtained on the beachbetween tide-marks; Port Curtis, 7-11 fms. (j^o. 85), severalspecimens.Other specimens are in the collection of the British Museum fromFaciug Island, Port Curtis (J. MacgiUivray, H.M.S. 'Rattlesnake');and a small example from Shark Bay, W. Australia {F. M. Rayner,H.M.S. 'Herald'), probably belongs here.This species is closely allied to the well-known New-ZealandP. elongatiis, M.-Edwards, but the chelipedes have a longer, slendererwrist, and the palm is slenderer and its outer margin is straight, notarcuated. The variety inermis is distinguished by Mr. Haswell byhaving two spines near the distal end of the posterior margin of thewrist, not three as in P. elongatus. De Haan in his description ofP. japonicus mentions three, but figures two only. The wrist is evenlonger and the palm more roughened above tlian in the Australianspecimens ; and the second pair of legs only has the merus-jointbispinulose at apex.The Japanese species Petrolisthes pidcliripes., designated by WhitePorcellana pulchripes (List Cr. Brit. Mus. p. 129, 18-17), of which thetype, from the Madjica-Sima group, is in the collection of the BritishMuseum, is closely allied to the foregoing ; but the chelipedes havea short thick carpus, which is much shorter than the cej^halothorax,and has three teeth on its posterior margin ; the distal end of themerus-joints of both second and third ambulatory legs is unarmed.12. Petrolisthes lamarckii {Leach).Here are referred several specimens found on the beach at FlindersIsland, and one obtained between tide-marks at Port MoUe (No. 103).These examples are of small size ; the front is triangulate, somewhatdeflexed, sinuated on the margins, concave in the middle line above,narrowed to the apex, which is rounded ; there is a very distinctpostocular s^jine on the lateral margins of the carapace ; the chelipedesare closely granulated above ; the arm has a blunt tooth at the distalend of its inner margin ; the inner margin of the wrist has threetriangular, not very distant teeth, which decrease in size from thefirst to the last ; at the distal end of the posterior margin are threesmall spines. Colour reddish or yellowish ; the first and . secondambulatory legs (where the coloration is best preserved) have the