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) (14759685086).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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urious fish (AmUyopsis spelceus), which lives inthe Mammoth cave, and which appears to want even theorbital cavity. The crawfishes (Astacus pelhicidus) of thissame cavern are also blind ; having merely the pedicle for theeyes, without any traces of facettes. 2. OF HEARING. § 145. To hear, is to perceive sounds. The faculty of per-ceiving sounds is seated in a peculiar apparatus, the EAE, which OF HEABDfG. if? constructed with a view to collect and augment the sonorousvibrations of the atmosphere, and convey them to the acousticor auditory nerve (fig. 45, 0), which arises from the posteriorpart of the brain (fig. 20). § 146. The ears never exceed two in number, and are placed,in all the vertebrata, at the hinder part of the head. In alarge pro-portion ofanimals,as the dog,horse, rab-bit, andmost of themammals,the exter-nal parts ofthe ear aregenerallyquite con-spicuous,and as theyare at thesame timemoveable,they be-come oneof the pro-minentfeaturesofthe physi-ognomy. § 147.These ex-
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Fig. 45.—Vertical Section of the Organ of Hearing inMan.—The internal parts are enlarged, to make them moreevident, a, b, c, the external ear; d, the entrance to theauditory canal,/; e, e, petrous portion of the temporal bone,in which the internal ear is excavated; g, membrane of thetympanum; h, cavity of the tympanum, the chain of bonestp*nnl n being removed; i, openings from the cavity into the cells,j, excavated in the bone ; on the side opposite the mem-pendages, brana tympani are seen the foramen ovale and foramen ro-however, tundum; k, the Eustachian tube ; /, the vestibule; m, the se-micircular canals ; n, the cochlea; o, auditory nerve ; p, thecanal for the passage of the carotid artery to the brain ; g,part of the glenoid fossa, for receiving the head of the lowr-rjaw; r, the style-like process of the temporal bone, whichgives attachment to muscles; s, the mastoid process of the do not,properlyspeaking,constitute the organ temporal bone. 72 SPECIAL SENSES. of hearing. The

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