( 267 ) 



TABLE XXXII. 



SYSTEMATIC SCITET or THE CHIEF STAGES ix THE DETELOITCEST 



The auditory nerre is an 



differentiation of the horn-plate, appears at a certain point on the skin of 

 the head. 



IL SeamdStage. 



The differentiated place of the horn-plate, at which the auditory nerve 

 appeared, forms a small special auditory groove in the skin, which has an 

 tar orifice in the appendage called the labyrinth." 



HI. Tkird Stage. 



The auditory groore has detached itself from the horn-lamina, and forms 

 a small cloeed anditory reside filled with flakL The "labyrinth-appendage*' 

 becomes rudimentary (Afmadmctna nxtibmli). 



IV. Pomrtk Stage, 



The auditory reside differentiates into two connected parts, the ear- 

 ponch (*tric*l**) and the ear-sac (saeenfef). Each of the two tmutni 

 receives a special main branch of the auditory nerre. 



V. Fifth Stage. 



Three semi-circular canals grow from the ear-pooch (as in all Amphi- 

 rAtM> 



VL Sixt* Stage. 



The u snafl" (eoeMm) grows from the ear-sac in Fishes and Amphibia . 

 it is rery insignificant, and is only developed as an independent part in the 



TH. 



The first gin-opening (the blow-hole of Selachians) changes into the 

 tympanic canty and the ******* tube; the former is externally closed 

 by the tympanic membrane (Amphibia). 



TUL Eighth Stage. 



The^maD bones of the ear (ptsicala mutt***) (the hammer (mlZnu) and 

 anvil (lam*) from the first gtO-arch, the stump (stapes) from the second) 

 derefcp from parts of the first and second gill-arches. 



IX. JTtat* 'Stage. 



The external ear is deroloped, together with the bony ear-canaL The 

 sheH of the ear is pointed and movable (as in most lower Mammals). 



X. Ten** Stage. 



The ear-shell, with its muscles, becomes disused and a rudimentary 

 organ. It is no longer pointed, but, on the contrary, has a carved rim with 

 a small ear-flap (as in Anthropoid Apes and Men). 



