554 THE RABBIT CHAP. 



III. Dissect off the muscles covering the mandible on the 

 side you are working ; detach its ascending portion from the 

 muscles inserted on its inner surface, remove it entire, cut- 

 ting through the symphysis, and clear away the underlying 

 muscles. Pass a probe from the cut end of the gullet for- 

 wards 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. 135). Note : 



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

 papilla (p. 507) ; c, the pharynx ; d, the glottis and epiglottis ; 

 e, the continuation of the pharynx above the velum palati 

 (nasopharynx), with which the internal nostrils communi- 

 cate ; /, the positions of the teeth (incisors and grinders) ; 

 g, the apertures of the naso-palatine canals. 



With a fine saw, make a longitudinal vertical section of 

 the entire head, cutting very slightly to that side of the 

 median line on which you are working, so as not to injure 

 the cartilaginous nasal septum. Pin down and finish 

 dissecting under water, noting again the parts just referred 

 to ( i) and also 



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

 away if the brain has been removed. 



3. The aperture of the Eustachian tube : pass a probe from 

 it into the tympanic cavity. 



4. The position of Jacob son's organ, on the ventral side 

 of the nasal septum ; and after cutting away the latter, the 

 olfactory nerve, ethmo-turbinal , maxillo-turbinal and naso- 

 turbinal of the other side (pp. 493 and 534, Fig. 135). 



Sketch the entire longitudinal section. 



IV. Remove the larynx with the anterior part of the 

 trachea. Make a longitudinal vertical section of it, keep 

 one half entire, and from the other dissect away the muscles 

 and mucous membrane so as to see the cartilages clearly. 

 Examine first the cartilages and then the soft parts, noting 

 the relations of the thyroid, cricoid, and arytenoid cartilages, 

 the epiglottis, and the vocal cords (p. 517). Sketch. 



G. The Brain. 



I. External characters. Note (Fig. 141) : 



1. The medulla oblongata, with its dorsal and ventral 

 fissures and the pons Varolii ; the convoluted cerebellum, 

 consisting of a central lobe and two lateral lobes and flocculi. 



2. The optic lobes, seen on slightly separating the hemi- 

 spheres and cerebellum ; the crura cerebri. 



3. The olfactory lobes ; the cerebral hemispheres (frontal, 



