LEPUS CUNICULUS 303 



behind these are a pair of small white spots surrounded by shallow 

 circular grooves and termed the circumvallate papillae. 



Opening into the buccal cavity by means of ducts are four pairs 

 of salivary glands whose function is to produce the -saliva the 

 action of which on the food has already been discussed in connection 

 with digestion. The infra-orbital glands are fairly large irregularly 

 lobate glands situated just below the eyeball. Their ducts pass 

 downwards to open on the inside of the cheek nearly opposite to the 

 second pre-molar tooth. The parotid gland is a soft mass on each 

 side just below the skin and lying in front of and below the base 

 of the external ear, between it and the mandible. Its duct, the 

 Stenonion duct, passes close beneath the skin parallel with the 

 zygomatic arch to open on the inside of the cheek near the preceding 

 duct. The sub-maxillary gland is a compact, red, ovoidal structure 

 situated just inside the angle of the mandible, and its canal, Wharton's 

 duct, runs along the inner side of the lower jaw to open midway 

 between the posterior incisors and the base of the tongue. The 

 fourth pair are the sub-lingual glands, elongated flattened red 

 bodies situated on the inner side of the ramus, between it and 

 Wharton's duct, near the openings of which their own ducts 

 terminate. 



The organs of Jacobson are two small tubular bodies 

 embedded in the front end of the hard palate just above the palatine 

 processes of the pre-maxillae. They communicate with the nostrils 

 in front and by means of the naso-palatine canals with the buccal 

 cavity. Their functional significance is not apparent. 



The buccal cavity passes backwards into the pharynx and 

 the point of transition is marked dorsally by the termination of the 

 soft palate, so that the posterior nares or ends of the narial passages 

 also lead into it, uniting to form one posterior nasal chamber just 

 before so doing. Into this chamber open the Eustachian tubes 

 leading from the tympanic cavities of the ears. On the floor of the 

 pharynx is a fairly large opening, the glottis, leading into the larynx 

 and so allowing air to reach the lungs. From the front wall of 

 this opening, a thin bilobed flap of cartilage, the epiglottis, projects 

 upwards into the pharynx. In swallowing, this flap is bent down 

 and so closes the glottis, preventing the entry of food. The pharynx 

 continues on into the oesophagus. It will be seen then, that the 

 Eustachian tubes, internal nares and laryngeal opening are all in 

 close proximity in Lepus, and this is the case in mammals generally, 

 hence certain diseases are liable to affect ear, nose and throat at 

 the same time. 



The oesophagus is a narrow dilatable tube running along 

 the neck and through the thoracic cavity close below the vertebral 



