In a paper on “The Physical Conditions under which the Cambrian and Lower Silurian Rocks were probably deposited over the European Area,” Mr. Hicks has recently put forth some opinions on the lowest fossiliferous rocks of Scandinavia and Russia, and their relations, as to age and stratigraphical characters, to those of Britain, which I think ought to be somewhat modified. The chief assertions in Mr. Hicks's paper are, that at the Pre-Cambrian period a large continent existed in Europe; that a subsidence began in the south-western part, and gradually extended to the north-eastern, which was not submerged until the Tremadoc group had been deposited over the western areas; and, finally, that the marine faunas migrated from the south-west. In order to prove these generalizations, Mr. Hicks makes a comparison between the most important Cambrian districts of Europe. He thinks that the British Cambrian rocks are the oldest, that the lowest Swedish beds are probably equivalent to the British Menevian group, and that the Russian are not older than the Arenig. Though the scantiness of the organic remains in some instances makes it very difficult, or, indeed, impossible to parallelize with certainty the oldest deposits of the various countries, it seems, however, from the palæontological facts already known, quite unquestionable that the lowest rocks of Scandinavia and Russia are older than Mr. Hicks has supposed them to be in comparison to those of Britain.

Specific Chars.—Polyzoarium composed of small cylindrical stems occupied by oval to hexagonal cells arranged usually in quincunx; or in oblique ascending lines; periphery of the cells erect, sharp, and granular; granules minute, numerous, and closely arranged. Here and there the angles between the cells are occupied by a small supplementary pore or pores, which are occasionally increased in number, and extend vertically between two contiguous cells, or uniting, give rise to an elongated narrow groove-like slit. Section circular.

The numerous excellent observations which have been made in recent years relative to the Palæozoic rocks in different countries in the Northern Hemisphere, require that we should now and again attempt to summarize the results obtained, and by that means bring before the mind more clearly any advance in our knowledge of past changes which has been made, as well as note those blanks which are still left for future investigations. In these considerations I cannot attempt to treat fully the various observations made, but I will endeavour to notice the chief results, or those points upon which new light seems to have been thrown.

The remaining shells figured on Plate IV. do not belong to the Scalidæ, but to families considerably removed. The form next described undoubtedly belongs to the family of Aporrhaædce, the rest are Rissoidæ.