[18/9]

From the close affinity between this species and the recent Scalpellum vulgare, we may confidently infer that the capitulum consisted of fourteen valves, which are all preserved in Mr Wood’s collection, with the exception of the infra-median latera and of the rostrum. This latter valve would, no doubt, be rudimentary, and it has been overlooked by naturalists even in the recent species. The chief difference, excepting size, between these two species, is in the form of the rostral and carinal latera, but unfortunately these valves are extremely variable. It might even be maintained, with some degree of probability, that S. magnum was only a variety of S. vulgare. The valves of 5 . magnum are all thicker, stronger, more rugged, and considerably larger than in S. vulgare. Taking / the largest scutum, tergum, carina and upper latera in Mr Wood’s collection, they are very nearly double the size of the same valves in the largest specimen o f S. vulgare seen by me, namely from near Naples, which had a capitulum eight-tenths of an inch in length; and they are more than double the size of the same valves in any British specimen. Scalpellum magnum probably had a capitulum one inch and a half in length.