ALBERT

Description: This new species that I have the pleasure to dedicate to Dr. H. C.\nDelsman, Director of the \xe2\x80\x9eLaboratorium voor het Onderzoek der Zee" at Batavia, finds its nearest ally in Ilyoplax lingulata (Rathb.), probably also in Il. tenella Stimps. and Il. formosensis Rathb. Ilyoplax lingulata, described by Miss Rathbun in: Proc. Biol. Soc. Washington, XXII, 108, 1909 and, with figures, in: Kgl. Danske Vidensk. Selsk. Skrifter, 7. Raekke, Naturvidensk. og Mathem. Afd. V. 4, K\xc3\xb8benhavn, 1910, p. 323, under the name of Cleistostoma lingulatum from an immature female found in the Gulf of Siam, was afterwards redescribed by Dr. Stanley Kemp in 1919 in his valuable Monograph of the Scopimerinae, this author having obtained two adult males and an ovigerous female from the Mergui Archipelago (Stanley Kemp, Notes on Crustacea Decapoda in the Indian Museum.\nXII. Scopimerinae, Calcutta, July 1919, p. 344 [Records of the Indian Museum, Vol. XVI, Part V, N\xc2\xb0 22]). It is on the authority of Miss Rathbun in: Proc. Biol. Soc. of Washington, Vol. 34, p. 156, 1921, that this new species is referred to the genus Ilyoplax Stimps., because in this paper the genus Tympanomerus Rathb. is considered by herself as identical with Stimpson\'s genus.\nIlyoplax Delsmani is a species of somewhat larger size than Il. lingulata, the largest of the 44 male specimens, that are lying before me, presenting a greatest width of carapace of 8,8 mm., while this number was only 5,4 mm. in the larger one of the two males of Il. lingulata: female specimens were not sent. As regards the general aspect of carapace and legs, both species agree with one another that is also proved by the measurements.\nThe carapace, the greatest width of which is almost one and a half as