. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. AUDITORY ORGAN 305 the two plates of the lamina spiralis ossea (Figs. 223, 224). On the free border of the latter they pass out, and break up into terminal fibrill» on the inner surface of the basilar membrane. The fibrillaB extend to the sensory or auditory cells, and these are stretched as in a frame between the firm supporting and isolating cells or bacilli. From the surface of the bacilli a resistant net-like membrane (mcmbrana reticulnris) extends laterally, and through the meshes of the latter the hairs of the audit
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. AUDITORY ORGAN 305 the two plates of the lamina spiralis ossea (Figs. 223, 224). On the free border of the latter they pass out, and break up into terminal fibrill» on the inner surface of the basilar membrane. The fibrillaB extend to the sensory or auditory cells, and these are stretched as in a frame between the firm supporting and isolating cells or bacilli. From the surface of the bacilli a resistant net-like membrane (mcmbrana reticulnris) extends laterally, and through the meshes of the latter the hairs of the auditory-cells project. The auditory cells are covered by a thick and firm membrane. Fio. 224.—THE ORGAN OF CORTI. (After Lavdowsky.) B, B, basilar membrane ; Ba, Ba, bacilli, or supporting cells; 6', membrane of Corti; Lo, Lol, the two plates of the lamina spiralis ossea ; Ls, ligamentum spirale, passing into the basilar membrane ; Mr., meinbrana reticularis ; X, auditory nerve with ganglion ; JV1, JV-, the nerve branching up into fibrilla- and passing to the auditory cells (G, (V) ; A', membrane of Reissner ; X«<, scala media. -the membrana tectoria s. Corti—which perhaps acts as a damper, and which arises from the vestibular lip of the lamina spiralis ossea. The whole extent of the basilar membrane consists of clear, thread-like and very elastic fibres, of which about 16,000 to 20,000 can be made out in Man. A true pinna or auricula (Fig. 225), attached to the border of the external auditory meatus and projecting freely from the head, appears for the first time in Mammals. It is present in Monotremes, and, more especially in Echidna, is in organic connection with the upper end of the hyoid1 by means of the 1 This fact appears to indicate a probable genetic relation between the auricula and the visceral Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these il
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