File:Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct - for the use of schools and colleges (1870) (14596105888).jpg

Identifier: outlinesofcompar00agas (find matches)
Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges
Year: 1870 (1870s)
Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884
Subjects: Physiology, Comparative Zoology
Publisher: London : Bell & Daldy
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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104 ORGANS OF DIGESTION. the urchins the mouth is for the most part armed with jawsand teeth, and the oral and anal openings, gradually becomingmore separate, occupy distinct positions on the shell; in Echinusand Cidaris, the mouth is found at the under pole, and theanus at the upper pole of their globular shells. Fig. 174 showsthe structure of a common urchin (Echinus esculentus); the test
Text Appearing After Image:
Fig. 174.—The anatomy of the Echinus esculentus. ts divided near its equator, and the small section is raisedto shew the mouth from above ; k, h is the lantern, with thepyramids and teeth; the esophagus (m) is long and delicate,and continuous with the stomach (») ; the first convolutionof the intestine is seen at o, and the second at q, r; therectum (s) terminates in the centre of the opening formed bythe circle of ovarial plates, and surrounded by the branching ECHI1STODERMS AND BRYOZOOA. 165 ovaries (t), which open by canals passing through each of thefive ovarial plates. The auricles surrounding the mouth (i)give attachment to the lantern ; the ambulacral avenues (e)give passage to tubular feet; the simple spines (a) armingthe shell are moved by muscles; the small trident spines, orpedicellarise (b), move like forceps, and the long tubular feet(c) are protruded by the injection of a fluid ; an oblong vesi-cle (/) opens near the mouth; the intestine is retained in situby a delica

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