Kappers, Teleostean ajid Selachian Brain. 7 



Chapter I. 



THE FORE-BRAIN, PROSENCEPHALON OR TELENCEPHALON. 



I. The Fore-brain of the Teleosts. 



The structure of the secondary fore-brain of the teleosts is 

 characterized by its simphcity as compared with that of the sela- 

 chians. Indeed, as we know from Rabl-Ruckhard's investiga- 

 tions, the pallium merely consists of a thin ependymal membrane, 

 from which it follows that we do not find here the complications 

 appearing in the selachians from the development of tracts and 

 centers in the mantle itself. 



If, however, in the lateral parts of the anterior lobes covered by 

 the pallium, there are hidden none of the nervous parts which in 

 higher vertebrates are situated in the pallium, as Studnicka and 

 Mayer maintain for the cyclostomes (but recently contested by 

 Johnston), a second question arises which may be treated quite 

 differently. Haller and Herrick consider these parts to con- 

 tain cortical areas, while Edinger is of the opposite opinion. I 

 shall have to recur to this matter after having described the fore- 

 brain and 'tween-bram of the fishes which I have exammed and 

 compared them with the selachians. 



If for the study of the external structure we consider the telen- 

 cephalon of Lophius as it appears in a series of transverse sections, 

 we find far in front (Fig. i, Plate I) immediately over the NN. 

 optici the lobi olfactorii, which in Lophius are short and compact 

 but in Gadus (Fig. vii, Plate I) are very long. These lobi olfac- 

 torii anteriores consist dorsally of an ependymal membrane and 

 over them part of the lobi cerebrales projects, as Edinger states 

 for Barbus fluviatilis and as is also mentioned by C. L. Herrick: 

 "the cerebrum overlaps the olfactory dorsally." 



Farther back the aspect alters in such a way that against these 

 masses first described a new mass appears, in Lophius (Fig. ii) 

 dorso-laterally; in Gadus (Fig. vii) more ventro-laterally, with the 

 pallium attached along the exact line of union between the two 

 masses. This line, as described by others, is always obvious 

 (Figs, iii, iv, v, vi, viii, ix, x), on account of the presence of a sinus 

 and of the attachment of the pallium, which is always visible here 

 (Bellonci, Macropodus viridiauratus; C. L. Herrick, Hap- 



