CEANIAL NERVES OF CAECILIANS 



499 



Figs. 5 to 7 Cross-sections through the head, right half, upper jaw, of Der- 

 mophis mexicanus; middle and posterior nasal region. X 12.5. 



Figs. 8 to 10 Cross-sections through the posterior nasal region of Herpele; 

 fig. 10 through the ej^eball; sections 115, 127 and 135. X 12.5. 



constitute the ventral division of the olfactory nerve. The dor- 

 sal division of the nerve arises from the anterior glomeruli, both 

 medial and lateral. 



Although, as shown by Burckhardt ('91), Lee ('93), and Norris 

 ('08, '13), the olfactory centers are double in the Urodela, periph- 

 erally there is no such sharp distinction. It would seem from 

 the condition in Amphiuma and Siren (Norris, '08, '13) that 

 Jacobson's organ is related to the ventral posterior glomeruli, 

 but that with the latter are also connected portions of the defini- 



