LEPUS 145 



the true roof of the mouth, and this passage opens into the 

 mouth behind the soft palate, by the secondary choana. The 

 floor of the mouth is occupied by a large soft tongue. Four 

 pairs of salivary glands secrete into the mouth. They are, the 

 parotid (just in front of the ear), the submaxillary (behind the 

 angle of the mouth), the infra-orbital (below and behind the 

 cheek-bone, and the sublingual (on the inner side of the lower 

 jaw). 



The Eustachian tubes open into the mouth near the 

 opening of the nasal passage, and behind them are the tonsils 

 which are remnants of the 2nd pair of visceral (1st branchial) 

 gill pouches. 



The pharynx connects with the larynx by the glottis, and 

 this opening is protected by a flap, the epiglottis. In breathing, 

 the soft palate is dropped, thus allowing air to come in through 

 the nasal passage and into the mouth, and the epiglottis is 

 raised, allowing the air to enter the larynx on its way to the 

 lungs. When swallowing is taking place, the soft palate is 

 raised, closing the nasal passage, and the epiglottis is forced 

 down and bars the way into the larynx. 



The oesophagus runs through the diaphragm to the cardiac 

 portion of the stomach. The other or pyloric portion of the 

 stomach opens into the duodenum, the opening being sur- 

 rounded by a sphincter muscle. The duodenum receives the 

 bile-duct and the pancreatic duct. The liver is large, and fits 

 close up against the posterior face of the diaphragm. It is 



Fig. 62. — Lepus : dissection of the vascular system seen from the ventral 



side. 



a, aorta ; ab, adrenal body ; al, anterior laryngeal nerve (branch of 

 vagus) ; am, anterior mesenteric artery ; c, carotid artery ; ca, cceliac artery ; 

 eg, anterior mesenteric sympathetic ganglion ; en, cervical nerve ; d, 

 diaphragm ; da, ductus arteriosus ; dn, depressor nerve (branch of vagus) ; 

 i, innominate artery ; isg, posterior cervical sympathetic ganglion ; /, 

 jugular vein ; /, larynx ; o, oesophagus ; p, pulmonary trunk ; pa, pulmonary 

 artery ; ph, phrenic nerve ; pv, pulmonary vein ; ra, renal artery ; rd, 

 ramus descendens (branch of hypoglossal nerve) ; rl, recurrent laryngeal 

 nerve (branch of vagus) ; rv, renal vein ; s, stomach ; sa, subclavian artery ; 

 ssg, anterior cervical sympathetic ganglion ; sv, subclavian vein ; sy, 

 sympathetic nerve-chain ; t, thymus gland ; th, thyroid gland ; tr, trachea ; 

 v, vagus nerve ; vet, vena cava inferior ; vg, vagus ganglion ; XII, hypo- 

 glossal nerve. 



L 



