The Limestones of the Yorkshire Oolites long ago attracted the attention of collectors from the remarkable beauty of some of the fossils which are preserved in them. We need hardly go back so far as the days of Lister and his lapides Judaici, but the Scarborough Catalogue, published in 1816, may arrest our attention for a moment.

The earliest attempt to describe the component beds of the English Chalk was made by W. Phillips in 1819: this is his well-known account of the cliffs between Dover and Folkestone, which is reproduced in Conybeare and Phillips' Geology (1822). He recognizes four divisions as follows:—

The following appear to be well-marked varieties of Microconchus pusillus.

1a.—Spirorbis (Micro.) pusillus, Martin, var. simplex, var. nov. (Plate VII. Fig. 8.)

Var. char.—The coil of the tube is open, lax, and imperfect, representing only a portion of the more developed coil; surface striæ very fine.

In these mountains to the north of the road leading from Glen Docherty to Auchnasheen, the gneiss rocks and mica schists of which they are mainly composed dip at a high angle, and have a strike averaging somewhere about N.W. to S.E.—in some places being nearly due N. and S., in others only a little N. of W. This strike, which is the normal one for the Pre-Cambrian rocks, and very unusual in the newer deposits, occurring here throughout so great a thickness of strata and over a wide area, when we take into consideration the fact also that the rocks themselves present the strongest resemblance possible to many of those found amongst the Pre-Cambrian rocks in the Western areas, furnishes very strong proof that we have here a re-appearance of the old Pre-Cambrian floor.

The dentition of Gymnura, an existing Insectivorous Mammal, may with advantage be compared with that of the Eocene Carnivora. The dental formula of Gymnura is typical:—

The only other existing Mammals which have 44 teeth are the Pigs and the Moles. But in Eocene times, this number, as first noticed by Professor Owen, was the rule, instead of being the exception.