File:A treatise on zoology (1900) (14593566550).jpg

Identifier: treatiseonzoolo03lank (find matches)
Title: A treatise on zoology
Year: 1900 (1900s)
Authors: Lankester, E. Ray (Edwin Ray), Sir, 1847-1929 Bather, Francis Arthur, 1863-1934 Goodrich, Edwin S. (Edwin Stephen), 1868-1946
Subjects: Zoology
Publisher: London : A. & C. Black
Contributing Library: Robarts - University of Toronto
Digitizing Sponsor: University of Toronto

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Text Appearing Before Image:
Fig. XIV. PZw<eu5 of EcTii ftocT/a wins (after Theel).About 75 times nat. size. Explanation of letters to Figs.XIV. and XV.—o.c, anterior coelom ;a.d, anterior dorsal arm; am, am-niotic invagination ; a.v, anteriorventral arm; Tic, hydrocoel; hy,hydropore ; l.-p.c, left posteriorcoelom ; 0, mouth ; oe, oesophagus ;p, podia ; ■pd, posterior dorsal arm ;p.v, posterior ventral arm; r.p.c,right posterior coelom ; s, spines ofEchinoid ; sp, spicules of Pluteus :sp, the same being absorbed ; st,stomach.
Text Appearing After Image:
ECHINODERMA—GENERAL DESCRIPTION 17 growing tube feet ;ind spines causes it to break through the outerwall (Fig. XV. 4). While this takes place the spicular skeleton ofthe Pluteus is al)sorl)e(l, and the body of the Plnfeas shrinks up toa sac on the aboral side of the young Echinoid (Fig. XV. 5). Thehydropore from the first opens on the dorsal surface, which becomesthe aboral side. The right posterior coelom is also under here,as in Stelleroids. The larval stomach becomes that of the adult,but a fresh mouth is formed in the centre of the hydrocircus,while the anus is a fresh formation at the aboral pole. It is easy to understand that, with this amniotic developmentin the body of the larva, most of the traces of the Peniadceastage have disappeared. There is, however, evidence of a preorallobe, while the coil of the intestine and the radiate structure ofthe hydrocoel, nerves, and gonads, bear witness to antecedentphylogenetic changes. On those changes light is thrown bypalaeontology, w

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