^{page 258 note 3} Mr. John Gray's very choice collection of Upper Silurian fossils has since been acquired for the British Museum.

^{page 259 note 1} Bulletins Acad. Royal Bruxelles, 1854; Geologist, vol. i., 1858, p. 12, plates i. and ii.; Geological Magazine, vol. ii., 1865, p. 163, plate v.

^{page 259 note 2} M’Coy's “Synopsis of the Carboniferous Fossils of Ireland,’ p. 172, pl. xxiv., fig. 5.

^{page 260 note 1} P. 35, pl. E, fig. 2, a, b, c, d.

^{page 260 note 2} Synopsis des E'chinides fossiles, p. 156.

^{page 260 note 3} Now in the British Museum.

^{page 261 note 1} When examined with a pocket magnifying glass, the plates of nearly all the specimens in the British Museum, now upwards of twenty in number, show a finelystriated ornamentation running in an obliquely-transverse direction across their surface. Probably the specimen examined by M. de Koninck may have been much rubbed upon its surface. In the publications of the Geological Survey of Canada, Decade III., “Figures and descriptions of Canadian organic remains,” Montreal, 1858, p. 72, Mr. E. Billings, the accomplished palæontologist to that Survey, has figured in a small woodcut and described an anomalous and imperfect Cystidean, under the name of Ateleocystites Huxleyi. From the figure and description we are inclined to think it may hereafter be shown to be the “posterior” surface of a cystidean, identical with M. de Koninck's Placocyslites Forbesianus; the more so as the plates are described by Mr. Billings as tranversely striated. But as the Canadian specimen is very imperfect, we think it would be very hazardous to assume from the figure alone that Placocystites (de Koninck, 1869) was synonymous with Ateleocystites, Billings, 1858.—Edit.

^{page 261 note 2} One of the specimens in the Museum shows at least nine plates on its posterior surface.—Edit.

^{page 261 note 3} Goldfuss Petrefact. Germ. Tome i. p. 213. Pl. lxiv. Fig. 6.