A manual of the Mollusca, or, A rudimentary treatise of recent and fossil shells . Tprints of a tortoise, near Montreal, in the Lingula Shale, or oldest fossi-biferous rock at present known. MANUAL OF THE MOLLUSCA. Chapter II. CLASSES OF THE MOLLUSCA. The mollusca are animals with soft bodies, enveloped in a mus-culai skin, and usually protected by a univalve or bivalve part of their integument which contains the viscera andseci-etes the sheU, is termed the mantle; in the univalves ittakes the form of a sac, with an opening in front, from whichthe head and locomotive organs project:
A manual of the Mollusca, or, A rudimentary treatise of recent and fossil shells . Tprints of a tortoise, near Montreal, in the Lingula Shale, or oldest fossi-biferous rock at present known. MANUAL OF THE MOLLUSCA. Chapter II. CLASSES OF THE MOLLUSCA. The mollusca are animals with soft bodies, enveloped in a mus-culai skin, and usually protected by a univalve or bivalve part of their integument which contains the viscera andseci-etes the sheU, is termed the mantle; in the univalves ittakes the form of a sac, with an opening in front, from whichthe head and locomotive organs project: in the bivalves it isdivided into two lobes. The univalve mollusca are encepJmlous, or furnished mth udistinct head; they have eyes and tentacula, and the mouth isarmed with jaws. Cuvier has divided them into three classes,founded on the modifications of their feet, or principal locomo-tive organs. 1. The cuttle-fishes constitute the first-class, and are termedcepJtalopoda,^ because their feet, or more properly arms, are at-tached to the head, forming a cu-cle round the Fig. Oral aspect of a Cephalopod. * From Cephale, the head and^o^^ feet. See the frontispiece aud pi. I. t Fig. 1. Loligo vulgaris, Lam. \. From a specimen taken off Tenby, by Bowerbank, Esq. The mandibles are seen in the centre, surrounded by thecircular lip, the buccal membrane (with two rows of small cups on its lobes),the eight sessile arms, and the long pedunculated tentacles (t), with theu* en-larged extremities or clubs (c). The dorsal arms are lettered (d), the funnel (f). CLASSES OF THE MOLLUSCA, 7 2. Ill i\\Qgasteioimda,^ or snails, tlic under side of the bodyforms a single musculai foot, on which the animals creep orglide.
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmollusks, bookyear185
