Twenty-two years ago, Mr. E. Billings, F.G.S., the late excellent palæontologist to the Geological Survey of Canada, completed and published Decade iii. of his “Figures and Descriptions of Canadian Organic Remains” (Montreal, 1858), containing an admirable monograph on “the Cystideæ of the Lower Silurian Rocks of Canada,” wherein (at pp. 72–74) he gives a clear and concise account of a very extraordinary fossil Cystidean, with a very poor woodcut figure of one side, the plates of which he clearly describes. To this fossil he gave the name of Ateleocystites Huxleyi. The specimen was obtained from the Trenton Limestone, near Ottawa, Canada. (See our Plate VI. Fig. 1.)

At the beginning of this century nothing whatever was known about the history of the Carnivora in the Eocene period. In 1825, in the second edition of his “Recherches sur les Ossements fossiles,” Cuvier described certain fossil bones from the Gypseous Series as belonging to a Carnivore allied to the Racoons and the Coatis. Ten years afterwards, having obtained a palate from the same beds, furnished with five teeth on one side and four on the other, he referred the palate, as well as the bones alluded to above, to a genus allied to Didelphis. De Blainville, in his “Osteographie,” founded on these bones a genus allied to the Badger, which he placed amongst the “Petits Ours” (Subursidæ), under the title of Taxotherium, while he referred the supposed Didelphoid teeth of Cuvier to a distinct genus, Pterodon, to which also he assigned a place in the same group.

In the following notes we propose to collect descriptions of some of the igneous rocks on N. Wales founded on the collections made by the late Prof. Sedgwick many years ago. It is hoped that it may be of interest to readers of this Magazine, as many students turning their attention to rocks find a want of information in text-books concerning precise localities in Britain for the occurrence of many interesting types. Following Sedgwick's steps may help them partly to what they require, while the microscopical analyses appended will doubtless prove an aid to beginners, besides being a definite record, as far as it goes, of some types of Welsh rocks.

Observations on Spirorbis.—In the foregoing history I have endeavoured to give a brief and clear outline of the views held by those who have made it the subject of their investigations since the time of W. Martin.

The rocks described by Mr. Davies in Notes 15–20 belong to the newer series, and were collected as nearly as possible at the points indicated in the sections. They are here described for comparison with the older rocks already referred to, and with the rocks to be further mentioned to the east of this line. I selected intentionally for examination those which appeared most highly altered, or otherwise to have any resemblance to the old rocks; as it is well known that Prof. Nicol considered them to belong to that series, and not to the newer groups. The petrological evidence as given by Mr. Davies proves that they are in no way allied to the gneiss rocks of the old formation, and that they are not sufficiently metamorphosed to be allied to any schists of known Pre-Cambrian age in these areas. These facts, combined with the physical evidence of the discordance in strike also almost everywhere apparent, seem therefore conclusively to prove that they cannot be of Pre-Cambrian age, but that they belong to a much younger series, and overlie the limestone group found along the west side of Glen Laggan.

In Dr. Callaway's letter, April, 1880, p. 188, last line, for as read us.