394 



THE BABBIT. 



The auditory nerve (Fig. 158, vin) develops very early, as 

 already noticed, and by the tenth day, if not indeed from its 



LA 



FIG. 157. A diagrammatic section across the head of an adult Rabbit, to 

 show the relations of the internal ear, tympanic cavity and membrane, and 

 the auditory ossicles. The section is drawn as seen from the front, and is 

 taken along a line joining the reference letters so and MN in Fig. 1C2 

 (p. 405). The external ears are cut short, close to their bases, and the 

 floccular lobes of the cerebellum, which lie between the three semicircular 

 canals of each side, are omitted entirely. (From Marshall and Hurst.) 



B, buccal cavity. BO, basi-occipital. C, cochlea. CA, right external carotid 

 artery. CE, cerebellum. E, external ear or pinna. EM, external auditory meants. 

 ET, Eustaohian tube. H, body of the hyoid. LA, right lingual artery. M. malleus ; to 

 its inner side are seen the incus and stapes. MN", mandible. MO, medulla oblougata. 

 N, posterior nasal chamber. P, soft palate. PO, periotic. S, post-tympanic proee-.- 

 of squamosal. SC. anterior vertical semicircular canal. SO, supra-occipital. T, 

 tympanic bone. TC. tympanic cavity. TM, tympanic membrane. 



earliest appearance, is intimately connected with the inner wall 

 of the vestibular sac. 



