Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/174

140 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 24, elsewhere, although in their distribution there is something peculiar. The definite separation into zones is rather difficult. The upper limestones, in which alone Am. angulatus is found, contain a varied fauna, with which there is nothing to compare in the beds below. It is certain, however, that only the lower part of this zone is here exposed. Am. Johnstoni, however, ranges through these and the limestones lower down, and is here the most characteristic Ammonite. The true Am. planorbis has as yet been found only in one bed ; but this is not separated from the others by any other features. The change to the oyster-bands is very marked in pit No. 3,. accompanied as it is by a cessation of microscopic fossils ; and the same may be said of the change into the white limestone beds below.

On comparing the " angulatus" fauna with that of Marton, it will now be seen how nearly allied they are — so much so that it is probable that a complete knowledge of both would prove them to be almost perfectly identical. As at present known, however, they present some decided differences. Of the 44 species recorded as certain from Marton, 23 are also found at Cliff; and it appears possible that an actual comparison of specimens would increase this proportion. Fifty-two species are here recorded as certain from the same horizon, excluding vertebrates and microscopic fossils; of these 15 belong to genera unrepresented at Marton. The difference consists chiefly in the