As some fifteen months must unavoidably elapse previous to the publication of the Silurian Supplement to my Work on the British Fossil Brachiopoda, it has been considered desirable to anticipate a part of its contents, relating to the recent discoveries of the Rev. Norman Glass, of Manchester, as to the spirals and their connecting processes and attachments in the Brachiopoda of the Upper Silurian rocks.

The fragments of jaws of Ornithosaurs from the Cambridge Greensand show a greater variety in size, form, and proportion than those from any other formation. The largest species were apparently the most singular in the shape of the snout, but after five-and-twenty years of collecting we still seem destined to know them only from fragments which, though extraordinary and suggestive, are tantalizing from their imperfect condition. It is impossible to tell whether the head was short or long, or what proportion it bore to the body, in the oase of these isolated specimens, but some of them, like the jaw-fragment which I am about to describe, show a power of tooth and massiveness of bone which could only have pertained to one of the most destructive and probably one of the largest of these animals.

In the tenth volume of this Magazine, a correspondence appeared upon the subject of “True and Apparent Dip,” which was started by Mr. Penning, and continued by several able geologists. The object of the present article is to call attention to another branch of the same subject. We are all acquainted with “Sopwith's Models,” in which are experimentally shown the outcrops, or “traces,” of plane strata upon variously curved surfaces. We now are about to refer to the outcrop of curved strata upon a plane surface. I was led to examine this question from the following circumstances.

The Oolitic Polyzoa have been very little studied in this country. They are badly represented in our museums, and no systematic account of them has been given by any English writer. Their remains, however, are both abundant and often well-preserved in the Pea-grit beds of the Inferior Oolite near Cheltenham, and in the Forest-marble beds near Bath. Some Inferior Oolite beds near Metz, and the Forest-marble beds near Caen in Normandy, are still more prolific, and the produce of these several beds has furnished a very full illustration of the more prevalent forms of this class which lived in the Oolitic seas.

The Blackband Ironstone, at present extensively wrought at Borough Lee, Dryden Vale, about 5½ miles to the south-east of Edinburgh, is a member of the Middle Division of the Carboniferous Limestone Series. It abounds in fish remains, most of them unfortunately in a fragmentary and scattered condition, nevertheless many of these are clearly new to science. Such of these new forms as are most distinctly marked I propose to notice in the present communication ; the list will, however, doubtless be considerably extended by additional patient research, and we may also hope, that some further light will be thrown on the fishes, to which some of these fragments belonged.