67 II-DESCRIPTION OE THE GENERA AND SPECIES. Sub-Kingdom—ECHINODERMATA. Division—ECHINOZOA. Class—EC HINOIDE A. Order—Palaechinoidea. Sub-order—Perisclioecliinidte. Obs.—In addition to the specimens hereinafter described as Archceo- cidaris? Selwyni, and Archceocidaris, sp)., a few fragments of spines have been met with, hut in no case sufficiently well marked or preserved to warrant description. A single plate has been found in the Permo-Carboniferous of the Rockhampton District, Queensland. Family—A B CHJEO CIDABIDAE. Obs.—This family is represented in our Permo-Carboniferous rocks by one genus only. It is unknown from Western Australia, but a single plate impression has been found by Mr. C. W. de Vis, in the Gympie Series, of the Rockhampton District, Queensland. Genus—ARCITiEOCIDARIS, McCoy, 1844. (Synop. Carb. Lime. Loss. Ireland, p. 173.) ARCiiiEOCiDAitis ? Selwyni, sp. nov. PI. XV, Pigs. 1-3. Sp. Char.—Test fully four and a half inches in diameter at the greatest periphery. Interambulacral plates very large, quite a quarter of an inch in diameter, with prominent rim-like edges; surfaces concave from the edges to the miliary rings, which, with the primary tubercles are large and