384 



THE SKIN AND THE SENSE-ORGANS. 



inner side into the posterior nares, or rather into the month. The 

 descending- arm extends only a short distance forwards, to terminate 

 near the point where the superior and inferior sinuses communicate 

 by only a narrow opening-. This sinus is on the whole broader in 

 front than behind, and has a general direction from without, in- 

 wards and forwards underneath the superior sinus. 



Fig. 238. 

 Ep d 



Tl. 



ok 



Fig. 239. 



Frontal sections through tlie nose of two 



tadpoles; after U. Burn. 



A Anterior naris. 



l> Cartilaginous floor. 



(,' Cutis. 



d Cartilaginous roof. 



Ep Epidermis. 



//*' Intermaxillary gland. 



yni Lower nasal gland. 



flitt Upper nasal gland. 



A* Maxillary sinus. 



I Concha narium (os lachrynmle). 



m Maxillary bone. 



MS Oral mucous membrane. 



ok Cartilage. 



mi Upper blind sac. 



h Pharyngeal gland. 

 K Nasal septum. 



se Septum between the upper and lower 



nasal cavity. 



m External blind sac. 

 T Trabeculae. 



Th Lachrymal duct. 

 in< Lower blind sac. 



(3) The lateral sinus (ftri) is situated in the partition between the 

 superior and inferior sinuses, or rather between the external chamber 

 of the upper sinus and the inferior sinus. The lateral sinus is tri- 

 angular in form, being narrow in front and broad behind; at its 



