536 THE RABBIT chap. 



noting (he reO-ac/or dii/di musc\e around the latter. (For the structure 

 of the eye, see p. 538.) Cut off the pinna, and clear away the muscles, 

 lie, cu\ering the tympanic bone: remove the entire tympanic and 

 puriotic bones (p. 475) in one piece, lay open the external auditory 

 passage, and very carefully and gradually cut away the outer wall of 

 both tubular and bulbous portions of the tympanic with the bone- 

 forceps. Note : — 



1. The tympanic membrane and the handle of the malleus ; and after 

 cutting away the former so as not to injure the latter, and removing 

 rather more of the bulla, make out — 



2. 'Jhe tympanic cavity ; the malleus, incus, and stapes ; the teiiso) 

 tympani and stapedius muscles ; and the aperture of the Eustachian 

 tube. Remove the auditory ossicles, noting as you do so the fenestra 

 croalis z.n& fenestra rotunda, and examine them under the low power 

 of the microscope : by cutting through the periotic with the bone 

 forceps, the position of the membranous labyrinth with the cochlea may 

 be made out. 



III. Dissect off the muscles covering the mandible on the side you 

 are working ; detach its ascending portion from the muscles in.serted on 

 to its inner surface, remove it entire, cutting through the symphysis, 

 and clear away the underlying muscles. Pass a probe from the cut end 

 of the gullet forwards into the mouth : lay open the gullet along this, 

 and pull the tongue downwards, so as to get a view into the interior of 

 the mouth (Fig. 125). Note: — 



1. a, The palate and velum palati ; b, the tongue and its papilla: 

 (p. 492); c, the pharynx ; d, the glottis and epiglottis ; e, the con- 

 tinuation of the pharynx above the velum palati (naso-pharynx), with 

 which the internal nostrils communicate ; f the positions of the teeth 

 (incisors and grinders) ; g, the apertures of the naso-palatine canals 

 (p. 490). 



Then remove the nasal, premaxilla, and maxilla of the same side, 

 noting the olfactory nerves and the turbinals ; and after passing a probe 

 backwards from the externa! nostril into the nasal chamber as far as 

 it will go, remove the turbinals on this side, so as to expose the 

 cartilaginous nasal septum. Also cut away all the remaining bone on 

 the same side of the middle line, slit up the naso-pharynx, and reduce 

 your dissection to a neat longitudinal section, noting — 



2. The cranial cavity, the roof of which will have been cut away if 

 the brain has been removed. 



