1399.] ON A IfEW CBTTSTAOBA.lS' FROM LAKE TAN-GANTIKA. 697 EXPLAJ!fATION 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. floweri, p. 654. Upper and side views of head. 3. Cylindrophis rufus, p. 656. 2. Oil a new Brachyurous Crustacean from Lake Tanganyika. By William A. Cunnington, A.R.C.S.^ [Eeceived April 26, 1899.] (Plate XXXVIII.) The Crab described in this paper was obtained by Mr. J. E. S. Moore, of the Eoyal College o£ Science, from Lake Tanganyika during his Ansit in the summer of 1896. The specimens were taken in fairly ^eep water — never less than 60, and fi'om 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, Mr. Moore informs me, were taken in Kifcuta 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-&\\e\\^ 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-f I'ontal crest, and from the nature of the external maxilhpeds, chelipeds, and ambulatory legs, their characters are distinctly those of the group of the Thelphusidse, in which, in consequence, they must be placed, although at auy rate the majority of its members are mainly terrestrial in habit. The diiferences which Mr. Moore's specimens exhibit, however, from any hitherto described form, are sufficiently great, I think, to warrant the institution of a new genus for their reception. I propose the name Llmnotheljphasa macidata for them, as sug-gesting, in the first place, then habitat, and in the second their characteristic spotted appearance. This being at present the only known form of its kind, it is not easy to decide which of its characters denote a generic distinction, and which a merely specific. Following, however, as far as 1 From the Biological Laboratory, E. Coll. Sci. Lond. Communicated by Prof. G-. B. Howes, F.Z.S.