62 



fissure between the buudles of the fila olfactoria from behind instead 

 of crossing the median division {n. olf. m.) as in Squalus and Mustelus. 



* The nerve has a gan- 



glionic enlargement near 

 the base of the bulbus. 



In Carcharias there 

 is a bundle of fila ol- 

 factoria connecting the 

 two divisions of the ol- 

 factory nerve. The new 

 nerve as it enters the fis- 

 sure branches unequally, 

 sending a small twig to 

 the connecting bundle, 

 and a main stem to the 

 lateral division. This main 

 stem dips into the mass 

 of fila making up the 

 lateral division, and, after 

 coming into contact with 

 the enveloping" membrane 

 of the capsule, continues 

 its course along the latter 

 in an autero-lateral di- 

 rection. From time to 

 time it gives off small 

 branches which penetrate 

 the investing membrane 

 of the capsule, and enter 

 the folds of the nasal 

 epithelium. The chief part 

 of the nerve reaches the 

 antero-lateral portions of 

 the cup and there dis- 

 appears within the ' nasal 

 membrane. 



In Lamna (?). — 



1 have also identified this 



new nerve with certainty 



in the brain of an undetermined Selachian, supposed, however, to be 



Lamna. Only a portion of the head, containing the brain, came into 



Fig. 25. Brain of an adult Carcharias littoralis, 

 from above, and front jrortion of the biain from 

 below, nat. size. 



