Fauna Simalurensis - Decapoda (Crustacea) - On two species of crabs from the Island of Simalur, one of which is new to Science

a. Thalamita bilobata n. sp. One male, collected February 1913 by Mr. Edw. Jacobson at Sinabang, on the island of Simalur, east coast of Sumatra. This species belongs to the Section I. B of the Key to the Indian species of the genus Thalamita in Prof. Alcock's „Materials for a Carcinological Fauna of India, N0. 4. The Brachyura Cyclometopa. Part II. Calcutta 1899, p. 73" and the nearest allied forms are Thal, quadrilobata Miers from the Seychelles, Thal. Admete (Herbst) var. intermedia Borr. from the Maldive Islands and Thal. pilumnoides Borr. from the lagoon at Minikoi. The carapace presents its greatest breadth of 18,5 mm. (Fig. 1) at the level of the marginal teeth of the 2nd pair, the external orbital angles are 17,75 mm. distant, the distance between the teeth of the 5th pair 18 mm.; the length, measured near the median incision of the front, exclusive of the abdomen, amounts to 11,75 mm., so that the carapace appears one and a half as broad as long. Upper surface depressed, flat, sloping slightly down towards the antero-lateral borders, towards the front, and, as usual, more strongly towards the postero-lateral borders. It is crossed transversely by fine, faint granular ridges, one, broken by the cervical groove, between the last spines of the antero-lateral borders, one, interrupted in the middle, across the middle of the gastric region, which anteriorly is defined on each side by three short ridges, an anterior pair separated only by the narrow frontal furrow, a second pair widely distant from one another, one and a half as far distant from the ridge across the middle of the gastric region than from the anterior pair, while a