The Cambridge natural history . ,): A, as seen from the ven-tral margin: B, from the leftside, with the mantle turnedback ; , f)Osition of an-terior adductor muscle; i,intestine; I, liver ; »», in,mantle. ( A B ventral to the anterior margin, accompanied l)y a correspondingnarrowing of the shell, until it arrives at tlie position seen inMollusca of the shape of Mya, Pholas, and Solen. In sedentaryor attached genera, Pccten, Cliama, Ostrca, the foot tends tol)ecome aborted. The hi/ssis f/Iand, secreting a byssus of horny tlireads, ischaracteristic of many Pelecypoda, and may .be
The Cambridge natural history . ,): A, as seen from the ven-tral margin: B, from the leftside, with the mantle turnedback ; , f)Osition of an-terior adductor muscle; i,intestine; I, liver ; »», in,mantle. ( A B ventral to the anterior margin, accompanied l)y a correspondingnarrowing of the shell, until it arrives at tlie position seen inMollusca of the shape of Mya, Pholas, and Solen. In sedentaryor attached genera, Pccten, Cliama, Ostrca, the foot tends tol)ecome aborted. The hi/ssis f/Iand, secreting a byssus of horny tlireads, ischaracteristic of many Pelecypoda, and may .be observed hj anyone in tlie common mussel. It occurs in the larvae of manyspecies which do not possess a l)yssus in the adult stage. Thepedal gland of many Prosobranchiates, wliicli secretes a tough andalmost thread-like slime, is possibly homologous with the I>yssusgland of bivalves. Nervous System The Mollusca possess a nerv;jus system, which usually consistsof a number of nerve centres or ganglia, linked togetlier l)y l)ands(the commissures) and sending out tlucad-like nerves whicliramifv into the various organs. The character of tlie nervous 202 NERVOUS SYSTEM GASTEROPODA system varies greatly in differ
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
