Manual of Conchology, Structural and Systematic (Volume 1); With Illustrations of the Species (Paperback)

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: its design: the imperfection of human judgment, the uncertainty arising from paucity of material in some cases, in others, perhaps, the bewilderment caused by its redundancy, are fruitful sources of error which will occasionally waylay and mislead the most honest, thorough and patient investigator. I cannot hope to escape them; but I shall take note of all corrections, as well as of such additional information as may hereafter become accessible to me, in order that these may he incorporated in appendices, or perhaps in additional volumes, to be published from time to time, whenever the accumulation of such material may render them necessary. I feel that the work I propose to undertake is a worthy one; that its completion will enable the Conchologist/or II, t f, rst time to identify and to learn the history of all the species in his cabinet without the necessity of consulting many extensive and costly monographies, besides thousands of fugitive papers. Towards the completion of this task I ask the sympathy and aid of all interested in Conchological pursuits. GEORGE W. TRYON, Je. CEPHALOPODA. ANATOMY. E.rli'rnal Feature. Cephalopod mollusks are immediately distinguished from all other classes of the mollnsca by the circle of acetabula or arms which surrounds the head; these may be regarded as homologous with the foot of the gasteropoda, With its margins produced into the eight or ten processes which are indifferently designated as arms, acetabnla or brachia. The extension of this modified foot around the mouth of the animal, its manifold uses in its economy and its high structural development, combine to place the cephalopoda at the head of the mollnsca. The mouth is supplied with a pair of calcareous or horny jaws, resembling in form the beaks of a parrot. The ...