MARINE CRUSTACEANS. 717 



Bonnier, op. cit. PI. VII. figs. 3, 4). The .strong muscles are conspicuous in their large but 

 shallow cavity. Below the maxillipeds is that which Bonnier designates as the lower cephalic 

 lamina. This in Gancricepvn eleyans, Giard and Bonnier, forms three lobes on either side 

 in such a way that the outermost are produced furthest backward and the innermost the 

 least far. In the present species the central piece, though pretty strongly emarginate, is 

 scarcely bilobed, and by extending back much beyond the two lateral pairs of lobes appears 

 to differ from the corresponding part in all the neighbouring genera. 



The vast marsupial plates attached to the minute first gnathopods have as usual the 

 anterior section underlying much of the maxillipeds, this part being produced on the inner 

 (upper) surface into a broad sculptured lappet overlying a piece of the plate's hinder section. 

 On the outer (ventral) surface the two sections pass smoothly into union, the upper one 

 having a convex groove near the proximal part of the leg. The first gnathopods differ from 

 the rest of the limbs chiefly in having the fifth joint smaller and more completely over- 

 lapped by the compact sixth joint. The second and third joints increase in size in the 

 successive pairs of limbs to the fourth peraeopods. In both the fourth and fifth peraeopods 

 the second joint is rather remarkable for the bulging of the two margins, and the thii'd 

 joint is greatly widened distally. 



The pleopods have the outer branch similar to the pleural laminae of the segment, but 

 smaller, and the inner branch very much smaller than the outer, with the margins a little 

 iiTegular, at least in the earlier paire, and perhaps in all. 



The uropods are single-branched, long and slender, very much crumpled in the spirit 

 specimen. 



Length 3 mm., with a breadth of about 2'5 mm. 



Locality. The specimen had been already extracted from the host, Tylocm-cinus styx, 

 which was taken at ' Hulule, Male Atoll, Maldives,' and which showed on the left branchial 

 region of the carapace the cavity that had been occupied by the parasite. 



The specific name is chosen in compliment to M. Jules Bonnier, whose finely executed 

 and instructive work on this gi'oup of the Isopoda has been more than once referred to above. 



In the same bottle with the specimen just described there were four other isopods, 

 which I am disposed to regard as belonging to the same species, although, as Sars rightly 

 argues. Idem propterea non est, quia captus ibidem. 



(/■. This minute creature bears a very near resemblance to the males of Cancricepon 

 elegans and Gnipsicepon edtvardsi, as figured by M. Bonnier. It would be an extraordinary 

 chance that the female parasite of Tylocarcinus should have reached England from the 

 Maldives, without a male of its own species, but accompanied by a male belonging to some 

 other species of the same family. 



The present specimen is probably not mature, since it has second antennae reminiscent 

 of the cryptoniscus-stage. The pleopods also are more strongly developed than in the adult 

 of Cancricepon elegans, but in correspondence with the bopyrian stage of that species. No 

 dorsal or ventral bosses were perceptible. 



The eyes are dark, longer than wide. The limbs all nearly alike, with the fourth and 

 fifth joints very small, the sixth compact. The terminal segment of the pleon is bilobed, 

 the lobes a little prolonged, each with a minute seta at the apex and another at the side. 



Length estimated at half a millimetre. 



92—2 



