Kappers, Tcleostean and Selachian Brain. 13 



on the upper side and constitutes the highest point of the lobi 

 anteriores. 



Now, from the striatum there originates the important bundle 

 of the teleostean fore-brain, the tractus basalts, also called tractus 

 strio-thala?nicus or pedunculus cerebri (Figs, vii, viii, ix, x and xi, 

 Plate I). The origin of this large tract extends as far forward as 

 the striatum itself, i. e., the beginning of it is visible in cross 

 sections in that part of the lobi anteriores which projects dorsally 

 over the tracti olfactorii before they have yet entered the cere- 

 brum (Fig. vii). 



Besides the areas mentioned above which are situated outward 

 and backward from the striatum, the striatum is enveloped medi- 

 ally by a large layer (^area parolfactoria) of a tissue which seems to 

 contain no ganglion-cells and through which the medial olfactory 

 fibers take their course. Thus the striatum itself remains clearly 

 recognizable both by its richness in ganglion cells and by its large 

 masses of fibers. The latter originate (or terminate) dorsally 

 both before and behind and, converging medio-basi-caudad, run 

 without decussation backward into the lateral portion of the 

 'tween-brain, where they terminate in the lobi inferiores under 

 and probably in the nucleus rotundus. The great extent of the 

 striatum and the tract which originates from it at its widest part 

 appears in Figs, viii and ix, in which we also see quite clearly the 

 line of union between its area and that of the area parolfactoria 

 and the area olfactoria posterior lateralis. 



I cannot decide whether we are to consider the tractus strio- 

 thalamicus as a single or a double tract. The latter opinion might 

 be confirmed by the fact that in the codfish one part of this tract 

 is rather strongly medullated and another part unmedullated. 

 With the methods which I have employed I cannot arrive 

 at a complete certainty on this question, which of late has been 

 generally answered in favor of a centripetal and a centrifugal 

 tract. 



Caudad, all the fibers of the tractus strio-thalamicus unite, in 

 part entering between the lateral and medial olfactory centers, 

 and form a compact bundle that runs along the median fissure of 

 the praethalamus and thalamus below the level of the tertiary 

 olfactory connections with the hypothalamus. Its connections in 

 the lobi inferiores will be described in the second chapter. 



