The identity of Cancer armadillus Herbst, 1790, a name not used since it was first established, is clarified. It is shown to be a species of Demania Laurie, 1906 (Brachyura, Xanthidae), a genus of poisonous Indo-West Pacific crabs. Herbst's species is regarded as conspecific with Demania bangladeshensis Ng, Huda & Banu, 1987, and the holotype of D. bangladeshensis is here designated as the neotype of Cancer armadillus. Demania indiana Deb, 1987, is also here regarded as a junior synonym of Demania armadillus.
Two new species of brachyuran crabs are represented in a recent collection from caves in southern Myanmar [= Burma]. Demanietta burmanica sp. nov. (Potamidae) is the third species of Demanietta Bott, 1966, recorded from the country, and is closest to D. renongensis (Rathbun, 1904) from Thailand, but differs in the form of the carapace and details of the male first gonopod structure. Pseudosesarma brehieri sp. nov. (Sesarmidae) is allied to P. edwardsii (De Man, 1887) and P. crassimanum (De Man, 1887), both from the Mergui Archipelago, but can be easily distinguished by the distinctive form of its male first gonopod.
The identity of the homolid Moloha alcocki faughni (Serène & Lohavanijaya, 1973), from the South China Sea, is clarified, and is here regarded as a junior subjective synonym of Paromola macrochira Sakai, 1916. The taxonomy and reliability of various generic and specific characters of P. macrochira are also discussed.