NERVUS TERMINALIS IN AMIA 73 



in the- adult. In a section cut sagittally through the head and 

 passing along the entire length of the olfactory nerve, the nasal 

 capsule and its mid-rib, one can see the main ganglion and the 

 scattered ganglion cells along the ventral side of the olfactory 

 nerve (fig. 9). About two hundred and fifty cells on a single 

 olfactory nerve were counted at this age. Nearly half of them 

 are in the main ganglionic mass or near it, while the remainder are 

 distributed almost uniformily from the ganglion rostrally to 

 near the anterior end of the nasal capsule. They lie beneath 

 the mid-rib rather than laterally under the secondary folds. 

 There are some thirteen of these secondary folds on each side 

 at this age, indicated by the number of undulations of the epi- 

 thelium in the section (fig. 9). As the figure shows, the cells are 

 practically all located between the anterior and the posterior 



olf.bulb 



Fig. 9. Diagram from camera lucida outline to show the distribution of the 

 ganglion cells of the nervus terminalis in young Amia 50 mm. long. Delafield's 

 hematoxylin. X 20. 



limits of the nasal capsule. One or two cells were found prox- 

 imally of the ganglion along the ventral margin of the olfactory 

 nerve, and two or three cells of the same appearance were seen 

 ventrally near the point where the olfactory nerve joins the bul- 

 bus olfactorius. 



In a series of Weigert sections cut transversely through the 

 head of a fish whose total length was 100 mm. the ganglion cells 

 along the olfactory nerve show quite well. Twenty cells were 

 counted on the two sides along the proximal part of the olfac- 

 tory nerves between the nasal capsules and the olfactory bulbs. 

 Most of these cells lie within the cranial cavity. However, three 



