ISBN: 9781231297759

RareBooksClub. Paperback. New. This item is printed on demand. Paperback. 198 pages. Dimensions: 9.7in. x 7.4in. x 0.4in.This historic book may have numerous typos and missing text. Pur… More...

RareBooksClub. Paperback. New. This item is printed on demand. Paperback. 198 pages. Dimensions: 9.7in. x 7.4in. x 0.4in.This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1845 Excerpt: . . . identity of those parts which enter into the composition of the segments of the thorax of hexapod Insects has already been admirably pointed out by Professor Audouin. The principles on which the changes take place, and the analogies which the appendages of the head bear to those of the other regions of the body, had previously been shown in the excellent researches of Savigny. My object, therefore, is now to develope still further the principles already laid down by these authorities, and to point out the existence of parts in the skeleton of the Myriapoda analogous to those which have been shown in Insects; and also to offer some additional proofs of the universality of the great laws of development by the aggregation and coalescence of contiguous structures, as shown most distinctly in the aberrant class, Myriapoda. Naturalists are aware that in all the Articulata the organs of support are on the exterior surface of the body, and consist entirely of certain portions of the tegument in which earthy matter is deposited and consolidated. This dermo-skeleton affords an unyielding surface of attachment for the muscles, and more or less completely encases the whole body. In the higher Articulata the original division of the skeleton into segments is less apparent than in the Myriapoda, in which each segment remains distinct throughout life. First, then, Of the Structure of the Segments. Every segment of the body, in its normal state, is formed of two arched surfaces, a dorsal and a ventral. Each of these surfaces is originally developed in four parts, two of which are sit uated on each side of the median line. The two middle ones of the four portions on the ventral surface (tab. XXXIII. figs. 1 and 2) unite very early to form the single middle portion of the v. . . This item ships from La Vergne,TN., RareBooksClub<