CEREBRAL (O.MMI.sSLKES IX THE VERTEBRATA. 



497 



the views of Ramon y Cajal and ISurckliardt upon the morphological aspect of the Amphibian brain, for 

 their conclusions arc obviously a tissue of guesswork. 



The account wliich Ganpp, profiting by the blunders of his predecessors, has been able to give is 

 clearly based upon the latest memoir of Ediuger {op. cif. 189(5) upon the forebrain ol' reptiles, which I 

 have discussed in an earlier jiart of this memoir. It is only natural under such circumstances that 

 Gaupp's conclusions regarding the Ani|)liii)ian lieinisphere are marred by the same errors, which I have 

 already e.\posed (ride supra) in Edinger's memoir. But in addition Gaupp commits some additional 

 mistakes which create great confusion. J might quote one example. The reptilian hemisphere presents 

 a basal notch which corresponds to the vallectdn Si//i:i/ of the mammalian brain. Edinsjer calls it the 

 fovea limbica. Gaupp adoj)ts this term, but applies it to the groove which separates the bulbus 

 olfactorius from the rest of the hemisphere ! 



A coroual section in the plane of tlie cerebral commissuves affords jievhaps the mo.st 

 satisfactory basis npon which to iustitnte comparisons witli other forms, and the Fro"- 

 may be adopted as a type, not because it is the most suitable Amphibian for comparison, 

 but simply because it is best known. The accompanying diaprram (fig. 32) represents 

 schematically the appearance of a coronal section througli the brain of the Erog in the 

 plane x-t/ of the explanatory diagram. There are two commissures — dorsal and ventral — 

 in the lamina terminalis as in the E-eptilia. The commissura dorsalis is disti'ibuted in the 

 dorso-mesial area of the section, whiclt consists of a mass of grey substance containing 

 diffusely scattered nerve-cells [hip.]. Tiie epithelial roof of the recessus superior is 

 attached on each side to a mass of grey substance (jx'ra.) through which the flln-es of 



Fijr. 3:^. 



Fifr. 33. 



c.c/. 



^pard.. 



recs. 



vM 



Transverse section throusL the brain of a Frog (Ihina) passing through the two cerebral commissures 



in the plane .r-»/, fig. 33. 



the commissura dorsaUs pass to reach the area la])elled hip. The relative disposition of 

 these various structures is so obviously identical with that which has been seen to 

 characterize the reptilian l)raiu tbat, in the absence of any reasons to the contrary, I 

 do not hesitate to call the dorsal area the homologue of the hippocampus, its commissure 

 the hippocampal commissure, and the mass labelled ^j«ra. the ^' paratermlnal body.'' 

 Upon histological evidence alone one would never have suggested the homology of the 



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