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Show 5 4 4 DR. J. G. DE MAN ON CRUSTACEANS [Dec. 12, 9. Distance between the extraorbital angles as long as the length of the carapace ; no epigastric lobes ...................................... affinis. 3. Both fingers with a tuft of hair proximally.............................. 10. 3. A tuft of hair in the finger-cleft and extending along the fixed finger; carapace hardly broader than long, depressed ; teeth of the antero-lateral border sharp and salient; inner angle of the wrist produced to form a long spine .......................... onyx. 10. Exognath of external maxillipedes, in the adult male, more than twice as broad as the ischium ; epigastric lobes wanting; a brush of stiffisli hair at the tip of the fixed finger r r eciem externally........................................................{Z .p ilo sa . 10. Exognath, in the adult male, not onee and a half as broad as the ischium ................................................................................. 11. 11. Upper surface of the carapace granulated near the anterolateral margins ; second and third antero-lateral teeth of the carapace not salient; epigastric lobes distinct; granulated ridge behind the frontal border distinctly separated from it in the middle ............................................................................. pusillus. 11. Upper surface of the carapace, which is broader anteriorly than that of pusillus, not granulated near the antero-lateral margins; second and third antero-lateral teeth more salient than those of pusillus-, epigastric lobes distinct; granulated ridge behind the frontal margin contiguous to it in the middle line ................................................................................. barbatus. Artificial key to the known females of the species of Ptychognathus. 1. Carapace hardly broader than long, front prominent, nearly straight......................................................................................... 2. 1. Carapace decidedly broader than long, front little prominent and distinctly sinuous.................................................................. 3. 2. Regions of the flat, though not particularly depressed carapace and epigastric lobes distinct; antero-lateral teeth of the carapace sharp and salient.................................................................. dentatus. 2. Regions of the much depressed and quite flat carapace hardly ( . . . . . indicated; no epigastric lobes ......................................... i rteaeltt. (_ andamamcus. 3. Upper surface of the carapace granulated near the antero-lateral margins; ridge behind the frontal margin distinctly separated from it in the middle; exognath of external maxillipedes distinctly less broad than the ischium .................................. pusillus. 3. Upper surface of the carapace, which is anteriorly broader than that of pusillus, not granulated near the antero-lateral margins; ridge behind the frontal margin contiguous to it in the middle; exognath of outer footjaws just as broad or very slightly broader than the ischium .................................. barbatus. P aluEm o n ( E u p a l ^e m o n ) l a r Fabr. var. ? (Plate XVIII. figs. 7-19.) One male and one female without eggs from a freshwater pool, Christmas Island. During the two or three last decennaries several carcinologists have regarded a more or less large number of described species of the subgenus Eupalcemon as synonyms or, at the utmost, as individual or local varieties of Palcemon (Eupalcemon) lar Fabr. (confer: de Man, in ‘ Notes from the Leyden Museum,' 1879, pp. 168-173; Ortmann, in ‘ Zoolog. Jahrbiicher (Spengel),' v. Abth. f. Syst. 1890, p. 724; Couti6re, in ‘ Annales Sciences Naturelles,' Zool. 8me s6rie, t. xii. 1900, p. 292, and other papers of the same authors). Several specimens of Pal. lar Fabr. from |