The Devonian rocks in Devon, like those of the Old Red Sandstone of which they are the equivalents, have been divided into three groups. Mr. T. M. Hall, writing in 1879, quoted no less than five separate classifications suggested for the beds of North Devon, nor has uncertainty been removed by the conclusions arrived at by geologists since that date. But we may for present purposes take the following as the nearest approach to a generally accepted succession:—

While examining the rocks of the Middle and Upper series for fossil plants during the past eleven years (1907–18), the results of which have already in part been published, other discoveries were made incidental to the work of collection of plant remains. Among these the discovery of fossil fish remains seems worthy of special notice.

Trilobites in common with all other Arthropods shed their more or less rigid external covering or exoskeleton periodically. To accomplish this ecdysis it is necessary for this covering to split somewhere; and it is highly probable that the facial suture was the line along which such splitting took place. There seems, however, to be a tendency to assume that all lines which served this purpose are homologous. This has introduced unnecessary difficulties into the study of Trilobite classification. The object of this paper is to do something towards the elimination of this source of error.

Essentially the pores of Megacystis are diplopores, for they are arranged in pairs. This is evident on the inner surface of a plate (E 16169, E 7671). Here each pore-pair lies in a shallow depression, and each pore again lies in a slight depression at the bottom of this (fig. 14). Compare Sinocystis yunnanensis (antea, p. 538).

In addition to the variability of the suture-line in a given species, mentioned previously, asymmetry of the elements on opposite sides of the same suture-line is very frequent and probably universal in so far as the minor frillings are concerned, which is only to be expected in organic beings. This phenomenon has lately been illustrated again in Lioceras by Horn, and in Dactylioceras by Swinnerton & Trueman. The latter authors also have some interesting observations on asymmetry associated with lateral displacement of the siphuncle which is of sporadical occurrence in Ammonites.

In 1915 a heavy concentrate of sand from an unknown locality in Siam was submitted to me for identification. The sand consisted of rather coarse grains of a dark mineral, and finer grains of ilmenite, monazite, tourmaline, zircon, and topaz, with some of the same dark mineral as that occurring in coarse grains.

At a meeting of the Geological Society on January 22 a section at Little Heath, near Berkhamsted, was described and discussed; but both in the papers and in the discussion attention was focussed on the lower part of the section, and the gravel, which is separated by about 6 inches of bull-head from the Chalk, was assigned to the Pliocene and correlated with the Westleton Beds of Prestwich. But the upper beds have an interest of their own, especially for the archæologist who is acquainted with the work of the late Mr. Worthington Smith; and it seems worth while to point out some striking resemblances to deposits in a line running north-east of the site in question. The Little Heath strata referred to are:—

For the last few years many geologists have been unable to keep in touch with the literature of their subject, partly owing to pre-occupation with war work of various kinds and partly owing to the spasmodic arrival in this country of non-British periodicals. The following short bibliographical notes on one limited branch of geological research have been put together in the hope that they may be of use to those who are now returning to their normal avocations, by affording them some idea of what has been done in America in the way of petrological investigation during the last few years. The list makes no pretence at completeness, since the compiler is himself suffering from the difficulties mentioned above, and the abstracts have purposely been made as short as possible, giving merely the barest indication of the contents of each paper, as a guide to readers who may desire to select what is of special interest to them. If the idea meets with approval it is hoped to publish from time to time similar compilations on other branches of geology.