NERVUS TERMINALIS: TURTLE 429 



cavity. This condition is illustrated in figure 7. There were 

 some indications of much finer strands also in this region, but 

 they were not sharply enough differentiated from the olfactory 

 strands to justify inclusion in the figure as part of an intracranial 

 plexus of the terminalis. 



After emerging from the cranial cavity, the nervus terminalis 

 is composed of several well-marked strands which continue par- 

 allel with the vomeronasal bundles, mesial and in part dorsal, to 

 the latter. A short distance from the point of emergence of the 

 nerve, its strands begin to form a plexus over the nasal septum. 

 Lack of silver preparations of the older stages made it impossible 

 to follow this plexus for any considerable distance, especially in 

 its more rostral part, where it becomes more complex due to 

 entrance of fibers from the trigeminus. It was very evident that 

 both the nervus terminalis and rami from the ophthalmic branch 

 of the V nerve take part in the formation of a plexus on the nasal 

 septum. 



Clusters of ganglionic cells (fig. 3) were scattered throughout 

 this plexus. Along the vomeronasal nerve there was a nearly 

 continuous mass of cells from the point where the nerve turned 

 ventrorostrally at the bulbus olfactorius, to the point where the 

 more profuse spreading out of the septal plexus began. A some- 

 what similar arrangement of cells along the vomeronasal nerve 

 was found by Johnston ('13) in Emys, but apparently the cells 

 were not so numerous as in Chrysemys. 



A fortunate Cajal preparation of an 8-mm. -total-length embryo 

 gave a very clear demonstration that the trigeminus forms a more 

 important portion of this septal plexus than might have been an- 

 ticipated. As shown in figure 4, which represents a reconstruc- 

 tion from fourteen serial sections cut in the sagittal plane, the 

 trigeminal portion of the plexus is formed by the ramifications of 

 the ophthalmic nerve. The fibers were stained quite uniformly 

 brown or black. They could be followed to the gasserian gan- 

 glion, with the beautifully stained cells of which they united. 



The nervus terminalis in this preparation is represented by a 

 few clusters of cells and some yellowish fibers. The cells could 

 not with certainty be distinguished from the mesenchymal cells, 



