274 FISH. [Vol. X. 



4. The community of origin of the precommissure, callosum, 

 and hippocampal commissure or fornix is shown and a slight 

 differentiation of the latter in the Desmognathiis is suggested. 



5. The existence of a ligamentum dentatiim has been demon- 

 strated in the adult and larval forms. In the latter, where the 

 myel but partially fills the spinal canal, the ligament assumes a 

 cord-like appearance with a peripheral and central attachment, 

 and supports the myel in its proper position. In the adult there 

 is no peripheral attachment, but in transections it appears as a 

 thickened pad against the wall of the myel between the dorsal 

 and ventral roots. 



6. The evidence as to the intermediate forms of the nerve 

 cells lying between the endyma and the peripheral boundary 

 of the cinerea, and their transition from the pyriform or uni- 

 polar to the fusiform or multipolar condition, and the apparent 

 reversal of transition of the cells as compared with those of 

 the spinal ganglia. 



7. The dichotomous arrangement of the dendritic branches. 



8. The identification in this animal of myelinic and amye- 

 linic fiber tracts by the Weigert and Golgi methods. The 

 amyelinic being confined to the prosencephal and the most 

 of the diencephal, and represented by the precommissure, cal- 

 losum, supracommissure, Meynert's bundle, and a portion of 

 the peduncular tracts. 



9. The discovery in larval and adult Desmognathus of three 

 distinct nerve trunks emerging from the spinal ganglia : the 

 ventral, dorsal, and latero-caudal, each including dorsal root 

 and ventral root fibers, and from the mixed nature of these 

 fibers in each trunk, the function of all three is doubtless the 

 same. 



10. The Mauthner fibers were demonstrable in an adult 

 specimen of the Desmognathus but less easily than in the 

 larvae. 



Ithaca, N.Y., June i, 1894. 



