Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/493

 jaunes of Antwerp and not in the Sables gris, with such species as survived to the glacial period in England, as species proper to the Red Crag. I doubt whether the circumstance of a shell being found double in the Red Crag is sufficient to identify it with that deposit, as, from the compactness of portions of the Coralline Crag, I see no reason why many should not have been transferred from one to the other without break.

Species probably derived from the Coralline Crag.

Terebratula grandis. Cancellaria mitraeformis.

Astarte Burtini. Chemnitzia costaria.

— Basterotii. Conopleura Maravignae.

— mutabilis. Dentalium costatum.

Cardita senilis. Erato Maugeriae.

Cardium decorticatum. Nassa labiosa.

Chama gryphoides. — prismatica.

Cyprina rustica. ? Natica varians.

Diplodonta dilatata. Odostomia plicata.

— ? rotundata. Pleurotoma carinata.

Donax politus. — semicolon.

Erycinella ovalis. Pyrula acclinis.

Gastrochaena dubia. Rissoa costulata.

Hinnites Cortesyi. Scalaria foliacea.

Leuconopsis Lajonkaireana. — fimbriosa.

Limopsis aurita. — varicosa.

Ostrea princeps. Terebra inversa.

— ? Panopaea Faujasii. — canalis.

plicata. Trochus Kicksii.

Pecten dubius. — villicus.

Pholadidea papyracea. Trophon alveolatum.

Venus ovata. — consociale.

Caecum mammillatum. Vermetus intortus.

I feel that much uncertainty must still attach to such a list ; and I may remark that Mr. Jeffreys takes the lesser number of 13 species as derived.

Allowing for this element, the result is that the species found in the Red Crag are as under : —

Number according to Mr. Wood's list 239

New species added by Mr. Jeffreys and Mr. Bell 79

Species regarded by Mr. Jeffreys as varieties 45

Species for the first time identified as recent by Mr. Jeffreys 46

Extraneous species 46?

Excluding the varieties and extraneous species, this leaves as proper to the Red Crag 234 species, composed as under : —

Total   Living   Extinct  Proportion of species. species. species. extinct species.

234 216 18 7.7 per cent.

or, including the extraneous species : —

273 240 33 13.7 per cent.

With regard to geographical distribution, Mr. Jeffreys shows that