On the Discovery of a New Genus of Cirripedia in the Wenlock Limestone and Shale of Dudley

Abstract

T he genus Chiton of Linnæus (established in 1758) is remarkable among the Mollusca from the aberrant form of its shelly covering. Dr. Woodward, in his ‘Manual of the Mollusca’ (p. 156), thus describes it:— “The shell is composed of eight transverse imbricating plates, lodged in a coriaceous mantle which forms an expanded margin around the body. “The first seven plates have posterior apices, the eighth has its apex nearly in front. “The six middle plates are each divided by lines of sculpturing into a dorsal and two lateral areas. “All are inserted into the mantle of the animal by processes (apophyses) from their front margins.” I may add that these plates are always unilinear, and that the two sides are symmetrical, such an instance as a Chiton with unsymmetrical or bilineal rows of plates being unknown (see Plate XIV. fig. 6). More than 200 species are known, occurring in all climates throughout the world, from low water to 25 fathoms; and it is interesting to find that upwards of forty species of Chitons are recorded by palæontologists in a fossil state, extending back in time to the epoch of the Lower Silurian. During the past month I have had my attention drawn by Messrs. E. J. Hollier and Charles Ketley to the two species of fossil Chitons which were described and figured by M. L. de Koninck (‘Bulletins de l'Académie Royale des Sciences, &c., de Belique,’ 26 me année, 2 me sér. t. iii. 1857*, p. 199, pl. 1. fig. 2), and