232 FISH. [Vol. X. 



impossible to refer in all cases to specific publications ; some of 

 the most valuable assistance has come from conversations and 

 from the many instructive lectures delivered by Professor B. G. 

 Wilder in general neurology. I am also under considerable 

 obligation to Professor S. H. Gage for cooperation and informa- 

 tion concerning the salamander that has been studied ; and to 

 Mrs. Gage for the use, by way of comparison, of her unusually 

 instructive series of sections through the head of Diemyctylus, 

 as well as for many useful suggestions in connection with my 

 drawings. The abundance and availability of the well selected 

 neurological literature in the University library have also greatly 

 facilitated my work. 



Description of Desmognathus Fusca. 



So far as the writer knows nothing has ever been done upon 

 the central nervous system of Desmognathus fusca, although 

 it is described by Cope as being " perhaps the most abundant 

 salamander in North America." It ranges throughout the 

 eastern district of the nearctic region and, according to Heil- 

 prin, is entirely restricted to the western hemisphere. It is 

 commonly known as the "dusky salamander" on account of 

 its dark color which ranges from a dark brown to black on the 

 back and is light or marbled on the belly. It has prominent 

 eyes and a somewhat compressed tail. 



This form was chosen, not merely on account of its easy 

 accessibility, but because its habits and activities in many 

 ways represent conditions intermediate between terrestrial and 

 aquatic urodeles ; and it may therefore be considered as rep- 

 resenting a fairly accurate type for this group. 



The adaptability of this animal to either aquatic or terrestrial 

 environment was tested in the following way : a newly caught 

 and vigorous specimen was immersed in a glass jar filled with 

 water from the tap ; in the mouth of the jar was placed a 

 strainer with its convex bottom projecting under the surface of 

 the water, thus preventing the salamander from getting any 

 air except that mixed with the water. He was kept in this 

 way and without food for two weeks, the water being changed 



