NERVES OF THE DOGFISH 



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('04, '05) finds in Spinax niger that the olfactory nerve in its 

 development is at first single, connecting the anterior ventral 

 part of the olfactory placode with the brain. Later by shifting 

 and extension of the olfactory pit the nerve becomes connected 

 with the dorsal part of the placode. Longitudinal Schneiderian 



Fig. 3 A similar section through the nasal capsule, cutting the extreme pos- 

 terior edge of the lamellae of the anterodorsal part of the olfactory cup. Sec- 

 tion 387. X15. 



folds appear, most complete near the nerve. Later a secondary 

 group of the folds appears and a secondary nerve connection with 

 the anteroventral part of the placode occurs. There results a 

 double chamber — one posterior, containing the primary folds and 

 related to the primary nerve, the other anterior, containing the 



