Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/426

Rh, living. Throughout the Celtic and Northern Seas.

40. Astarte sp.?

, fossil. There is a species in the Bridlington beds, resembling the var. Scotica of danmoniensis, but with more numerous ribs, which I regard as distinct. Is this a smooth-margined variety of the shell which Professor Macgillivray describes from the coast of Aberdeen, and refers to Astarte sulcata of Montagu?—History of Molluscous Animals of Aberdeen, &c., p. 259.

41. Astarte compressa (Venus sp.), Montagu.

Astarte angulata, Woodward. Venus Montagui, Donovan. Cyprina compressa, Turton. Astarte multicostata, Macgillivray (non Smith). Crassina convexiuscula, Brown.

Var. β (latior). Crassina multicostata, Smith. Astarte compressa, Macgillivray.

, fossil. Frequent in all the glacial formations. Bridlington. Mammaliferous crag of Thorpe. [Sweden, Russia.]

, living. Throughout the Northern and Celtic Seas. Seas of Boreal America. The var. β is now especially northern, and in the fossil state is the most abundant form.

Note. Astarte compressa appeared in the coralline crag sea.

42. Astarte pisiformis, Searles Wood.

, Astarte trigonella, Nyst?

, fossil. An undescribed species found in the mammaliferous crag of Bramerton, and in the two preceding crag formations. "Astarte pisiformis is probably A. trigonella of Nyst, pl. 6, f. 18, though his species is not crenulated. It may be a young state, or, what is as probable, a sexual difference." Mr. Searles Wood (in lit.).

[43. Astarte laurentiana, Lyell.

Described and figured in Mr. Lyell's 'Travels in North America,' vol. ii. p. 160. From the glacial beds of Canada].

44. Cyprina islandica (Venus sp.), Linnæus.

Cyprina maxima, Searles Wood. Cyprina vulgaris, George Sowerby. The identity of this species with Cyprina æqualis of the Mineral Conchology has lately been disputed by Professor Agassiz. Extreme specimens of each are certainly easily distinguishable. Mr. Searles Wood, however, regards them as one species, and no naturalist has had such opportunities of forming a correct opinion. In a note to his 'Catalogue of Shells from the Crag,' in the sixth volume of the 'Annals of Natural History,' he remarks:—"The umbo of this (Cyprina islandica), from the coralline crag, is a little more produced, and appears to have been a thicker shell than the recent, which is the only difference I can detect, while the specimens from the red crag preserve a sort of intermediate character in that respect" M. Nyst also regards Cyprina æqualis as a variety of C. islandica.

, fossil. Common in the British glacial deposits. In the mammaliferous crag of Southwold. [Denmark.]