Kappers, Teleostean m^d Selachian Brain. 9 



Thynnus and some other adult Lophius, however, I again found 

 the uncrossed tract, so that we must assume that both occur and 

 that probably the uncrossed course of the lateral fibers is the more 

 general one, as it has been described by Bellonci, Edinger and 

 C. L. Herrick. It would be interesting to find out the conditions 

 which determined this different behavior. 



In following the course of the medial olfactory fibers we see that 

 they soon divide into two parts (Lophius, Gadus, Salmo, Thyn- 

 nus). The part farthest medial in Gadus is the smaller and more 

 heavily medullated; the other farther lateral is somewhat larger, 

 but less medullated. They are but slightly separated when they 

 enter the cerebrum and both run parallel to the median fissure, the 

 medial somewhat lower than the lateral. Before they reach the 

 commissura anterior (Fig. ix) they are farther separated and from 

 this point pursue quite different courses. 



The larger less heavily medullated fasciculus of the medial 

 olfactory tract decussates — at least pa.rtly — earlier than the smaller 

 more heavily medullated fasciculus. The decussation of the 

 latter fibers, moreover, takes place at a somewhat higher level, 

 though originally they lay lower. The greater part of these last 

 fibers terminate after the decussation more laterally and in many 

 fishes seem to end in the area olfactoria posterior lateralis, as 

 Goldstein describes, which again I can confirm for Salmo, but 

 not for the other fishes which I have examined. In the others the 

 fibers do not reach so far as the lateral area but end in the medial 

 part of the fore-brain, directly adjacent to the terminus of the less 

 heavily medullated fasciculus which crosses before and under 

 this decussation. The region where these medial olfactory fibers 

 end will be termed the area olfactoria posterior medialis, or epi- 

 striatum, as it is designated on the plates, a name, however, which 

 Professor Edinger, Goldstein and I have thought better to give 



"P- . ... 



Accordingly, the secondary olfactory connections in the fore- 

 brain of teleosts can assume two forms which are represented in 

 the diagrams on Plates VIII and IX. The two secondary 

 olfactory centers form probably one region that lies on the lateral 

 and caudo-dorsal side of the striatum and of which in some fishes, 

 like Salmo, the lateral connections are better developed and in 

 others the medio-caudal. Together they cover a part of the stria- 

 tum, whose highest part, accordingly, overhangs the olfactory lobes. 



