On the Pcrilymijhatic Spaces of the Ainplii1)iaii Ear. 



235 



brations to the endolympli. In addition to its connection with the 

 spatium sacculare by means of the ductus perilymphaticus, the recessus 

 partis basilaris has associated with it a special aperture in the floor 

 of the auditory capsule, opening into the anterior region of the fissura 



Sinus superior utriculi 



Ductus 

 pGi'ilymphaticHS 



Pars neglecia 



Recessus partis 

 neglectae " 



Spatium iiieniiigeale ■ 



Ductus reuuiens / i \ Saceuhis 

 ! * 



Foramen perii ymphaficwn \ "^'^^ iasilans 

 inferiiis ' 



Recessus partis basilaris 



Diagram 2. 



^ Spatinin sacculare 



-- Canaìis lateralis 



Fenestra vestibuU 



Foramen peri- 

 lymphatirAmi supe: 



Foramen perilymph, 

 accessorium 



Foramen perilymphaticum 

 inferius 



Fenestra vestiinli 



Diagram 3. 

 Diagrams 2 and 3. Constructed like Diagram 1. 2 represents the condition in 

 larva of Pelobates fuscus (44 mm). It forms an intermediate stage between 1 and 3. 

 3 represents the adult condition in Rana fusca and Pelobates. The ductus reu- 

 niens now passes into the cranial cavity to join the ductus perilymphaticus. I have 

 labelled the aperture through which it passes, the foramen perilymphaticum ac- 

 cessorium, to indicate its origin. At an early stage it becomes part of the fissura 

 metotica. Tympanal areas and perilymphatic tissue as in 1. 



