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Show 1899.] ON A NEW CRUSTACEAN FROM LAKE TANGANYIKA. 697 EXPLANATION OF THE PLATES. PLATE XXXVI. Trionyx subplanus, p. 619. PLATE XXXVII. Fig. 1. Typhlops albiceps, p. 654. Upper and side views of head. 2. T. fioweri, p. 654. Upper and side views of head. 3. Cylindrophis rufus, p. 656. 2. On a new Brachyurous Crustacean from Lake Tanganyika. By WILLIAM A. CUNNINGTON, A.R.C.S.1 [Eeceived April 26, 1899.] (Plate XXXVIII.) The Crab described in this paper was obtained by Mr. J. E. S. Moore, of the Royal College of Science, from Lake Tanganyika during his visit in the summer of 1896. The specimens were taken in fairly deep water-never less than 60, and from that to 500 feet deep. I have had in all seven individuals to examine, of which three are adult males, two adult females, and the remaining two young ones. All these specimens, M r . Moore informs me, were taken in Kituta Bay, at the southern end of the Lake, but he has also seen these Crabs near Kinyamkolo, also in the south, and Sumbu, some 100 miles up the western coast. They are often found clinging to Neothauma-shells and other objects, and are very active in habit. Their deep-water habitat is at first sight misleading; but a careful examination shows that from the presence of a post-frontal crest, and from the nature of the external maxillipeds, chelipeds, aud ambulatory legs, their characters are distinctly those of the group of the Theiphusidse, in which, in consequence, they must be placed, although at any rate the majority of its members are mainly terrestrial in habit. The differences which Mr. Moore's specimens exhibit, however, from any hitherto described form, are sufficiently great, I think, to warrant the institution of a uew genus for their reception. I propose the name Limnothelphusa maculata for them, as suggesting, in the first place, their habitat, and in the second their characteristic spotted appearance. This being at present the only known form of its kind, it is not easv to decide which of its characters denote a generic distinction, and which a merely specific. Following, however, as far as J From the Biological Laboratory, E. Coll. Sci. Lond. Communicated by Prof. G-. B. H O W E S , F.Z.S. |