50 journal of Comparative Neurology and Psychology. 



nearly as far as to the commissura posterior. Their observations 

 in this matter evidently do not agree. 



The relations as they are found in Galeus are as follows: In 

 Fig. Ixviii one sees a considerable quantity of clear unmedullated 

 bundles gather from the furrows of the saccus vasculosus in the 

 dorso-caudal wall of the lobi inferiores from the saccus epithelium. 

 In Fig. Ixvii this system (first neurone) runs upward and forward 

 until it ends on the same side in two ganglia (Fig. Ixvi). These 

 ganglia, which, as far as I know, are not described by other 

 investigators, except Goronowitsch and Johnston who saw 

 them in Acipenser, I shall call, "ganglia sacci vasculosi," as they 

 receive their fibers from the saccus vasculosus. They consist 

 partly of round cells and partly of middle-sized polygonal cells 

 and they are abundantly provided with blood-vessels. From 

 each of these ganglia fibers cross the median line, of which it is 

 difficult to say whether they are a commissure between the ganglia 

 or a crossing of fibers of the second neurone which go upward. 

 The latter interpretation seems to be the most probable. It 

 seems to me that this commissure is also found m the teleosts, 

 where these fibers decussate before passing upward. Neither 

 they nor the saccus itself, however, are as large as in the sela- 

 chians; nor could I find there a separate ganglion, but only small 

 round cells dispersed between the fibers of the first neurone. The 

 fibers of the second neurone of the saccus sense-organ, which are 

 also unmedullated, end probably in the substantia grisea centralis. 

 It is impossible to follow them any farther, at any rate, on account 

 of the great quantity of fibers between which they run. 



Besides this decussation, there is a second decussation in that 

 region. Near the ganglia of the saccus there is a considerable 

 mass of cells in the lateral, dorsal and ventral walls of the lobi. 

 Haller has given a very exact description and sketch of their 

 ventral layer under the name of "ventrale Zwischenhirn Kern," 

 which passes over dorsally into the "Vereinigungsgebiet" of this 

 author. From this cell mass, which is much larger dorso- 

 caudally (Haller's Vereinigungsgebiet) than ventro-frontally, 

 a great many medullated fibers gradually assemble, of which one 

 part connects the largest masses of this cell region, a connection 

 which I shall call the coin, postinfimdihularis superior. This 

 commissure (Fig. Ixv) lies dorsal to the com. postinfundibularis 

 inferior, is medullated and broader, but less compact than the 



