Bedford, Olfactory\Ncn'e in Swhic. 



407 



In stages of eighteen millimeters and over, the olfactory 

 nerve is seen to be double and is connected with the olfactory bul- 

 bus by means of two roots, median and lateral, from each of 

 which arise a number of filaments passing to the olfactory epi- 



fiig. 14. Sagittal section of a swine embryo, 17 mm. in length, showing 

 converging filaments {fila olfactoria) of the olfactory nerve. 0. L., olfactory lobe 

 N. E., nasal epithelium ; F. O., fila factoria; C. M., cellular mass overlying the 

 olfactory lobe. X 93/^- 



thelium. These main divisions are apparently homologous to 

 the two divisions described by many observers for the sela- 

 chians. 



Summary. 



1. At the time of the formation of the olfactory plate, 

 there is no trace of either cerebral hemispheres or olfactory 

 lobes. 



2. The olfactory plate shifts from a more dorsal to a more 

 ventral position. 



