DOGFISH. 21 



of the medulla, just below the corpus restiforme and pars- 

 ing forward to supply the 'face.' Just behind this are 

 the combined facial and auditory nerves which supply the 

 face and ear. Still farther back is the large vagus arising 

 from the side of the medulla and going to the gills, the 

 lateral line of the trunk, and the heart and stomach. 

 Trace these nerves as far as possible and add them to the 

 sketch of the brain. 



Cut off the snout by an incision passing through the 

 nostrils, and in the cut surface see the folds of the olfactory 

 membrane. What reason can you suggest for the folding? 

 Sketch the cut surface. 



Have you found bone in any part of the dogfish? 



