Illustrated Index of British Shells / Containing figures of all the recent species

by G. B. Sowerby

15. C. costulata, Risso.—Exmouth, Cornwall, Swansea, Herm. Wedge-shaped, marbled, strongly-ribbed.

16. C. rhombea, Berkley, (Modiola.)—M. Prideauxiana.—Guernsey, Torbay, Penzance, etc.; coralline, R.

17. C. decussata, Montagu, (Mytilus.)—C. and Modiola elliptica, cicercula, and faba.—Scarborough, and a few northern localities, 5 to 50 fath., Mc.; Norway, etc. Subquadrate, decussated, minute.

Mytilus, Linn.

18. M. edulis, Linn.—M. vulgaris.—Brit. co. generally, Cc. Byssal margin swelled.

19. M. ungulatus, Linn. Syst. Nat.—M. edulis, var. M. incurvatus (Hoof-Mussel).—Cornwall, Guernsey, etc., Mr. Byssal margin bent inwards, lower margin broad and straight.

20, 21. M. galloprovincialis, Lamk.—M. edulis, var. M. dilatatus?, M. pellucidus? (young, f. 21), M. subsaxatilis?—British Channel, etc., C. Dorsal margin dilated, beak advancing.

PLATE VIII.