﻿158 



SUPPLEMENT TO THE CRAG MOLLUSCA. 



fragmentary) in the Middle Glacial at Hopton, and in all these deposits it is the thin and 

 non-rngose form that occurs. At Bridlington I believe it is not uncommon, but there 

 and at Dimlington it is the gigantic rugose form that occurs. 



Saxicava? fragilis, Nyst. Crag Moll., vol. ii, p. 288, Tab. XXIX, fig. 6. 

 Localities. Cor. Crag, Sutton, and near Orford. 



This shell was described by Montague under the name Mytilus plicatus ; but plicatus 

 of Chemnitz is a different species inhabiting the Nicobar Islands. I have, therefore, 

 retained Nyst's name for our shell. 



There are two or three small bivalves which have been hitherto called by different 

 generic names, and have as yet no proper resting-place, and which I consider ought to 

 have a distinctive generic appellation of their own. The first of these is the above 

 fragilis. Another is Saxicava ? carinata (' Crag Moll.,' vol. ii, p. 289, Tab. XXIX, fig. 

 5), which I believe to be specifically distinct from fragilis; while it seems probable that a 

 fossil of the older tertiaries of America called by Lea (' Contrib. to Geol.,' p. 48, pi. i, 

 fig. 1 6) Byssomia petricoloides may prove a third ; but the hinge of Lea's specimen is 

 not perfect. 



The subjoined list of synonyms shows how the first of these shells, fragilis, has been 

 bandied about from genus to genus : 



Mytilus plicatus, Mont. Test. Brit. Suppl., p. 70, 1808. 

 Saxicava plicata, Turt. Brit. Biv., p. 22, 1822. 



— ? fragilis, Nyst. Coq. Foss. de Belg., p. 97, PI. 4, fig. 10 a, b, 1843. 



— rugosajuv., Forb. and Hani. Brit. Moll., vol. i, pi. 6, figs. 1 — 3. 

 Sphenia cylindrica, S. Wood. Catalogue, 1840. 



Magdala plicata, Gray. List of Brit. Biv., p. 161, 1851. 

 Anatina — id. Ann. of Philos., 1825. 



Fsammobia? — Jeffreys. Ann. and Mag. Nat. Hist., vol. xix, p. 314. 

 Lyonsia — Forb. and Hani. Brit. Moll., vol. i, p. 218, 1853. 

 Panopea — Jeffreys. Brit. Conch., vol. iii, p. 75, 1865. 

 Myrina oceanica, Conti., 1864. Fide Jeffreys, Brit. Conch., vol. v, p. 192. 



Sphenia ovata? Crag Moll., vol. ii, p. 276, Tab. XXIX, fig. 7 (as S. Binghami). 

 Locality. Cor. Crag, Sutton. 



The shell figured in the ' Crag Mollusca ' was referred with doubt to the recent 

 British species Binghami. Dr. P. Carpenter, however ('Geol. Mag.,' vol. ii, p. 153), says 

 that the Crag shell more resembles Sph. ovata from the north-west coast of America. 



