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A History Of British Mollusca And Their Shells
A History Of British Mollusca And Their Shells Author:Edward Forbes, Sylvanus Hanley Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: PHOLADIDEA, Leach. Shell more or less globose or oblong, equivalve, inequilateral, surface of valves similar to those of Pholas; their beaks not covered by ca... more »llosities ; accessory plates small. Muscular impressions as in Pholas. Anterior extremity open in the immature, but closed in the adult shell by a thin papyraceous permanent shelly coat, with a small opening centrally and anteriorly for the foot. Posterior extremity truncated and gaping, usually furnished with an expanded coriaceous cup. Animal claviform; the mantle closed in front, except a small opening for the passage of a truncated sucker- shaped foot. Siphonal tube long, terminating in a disk surrounded by cirrhi, encircling the openings of the branchial and anal siphons, each of which are also surrounded by radiating cirrhi. The separation of the calyciferous Pliolades from their allies of the last-described genus, was, we believe, first suggested on conchological grounds, by Dr. Goodall to Dr. Turton, who, in his " Conchological Dictionary," gives the name of Pholadidea Loscombiana to our British species. In the thirty-ninth volume of the " Diction, des Sciences Naturelles," the group is characterised under the name of Pholadidea, and made a sub-genus of Pholas. Swainson, in his "Elements of Conchology" (1835) called the genus Pkolidea, and in his more recent " Treatise on Malacology" in Lardner's Cyclopedia, writes it Pholidata, and refers to Leach as the founder. The genus is a good one, seeing that both shell and animal afford excellent distinctive characters, which are presented equally by British and exotic species. The remarkable cup-shaped appendage surrounding the base of the united siphons may be regarded as a rudimentary tube for their protection—especially for the protection of the complicated ci...« less