CEREBELLUM OF URODELE AMPHIBIA 13 



AMPHIUMA 



I have examined the brain of a small specimen of Amphiuma 

 means 42 cm. long, cut into horizontal sections and stained with 

 iron hematoxyUn and acid fuchsin, and I find the relations here 

 essentially as in Necturus, though with some modifications in 



detail. 



The blind anterior diverticulum of the lateral recess of Amphi- 

 uma extends farther forward than in Necturus (cf . figs. 29 and 21) 

 and its roof is wholly membranous instead of massive (fig. 28). 

 The plexiform lateral evagination from the recessus is much more 

 extensive than in Necturus and extends forward almost to the 

 posterior pole of the cerebral hemisphere. At the ventral part of 

 the rostral end of the auricular lobe the central grey layer reaches 

 the surface and the stratum album (moleculare) is there entirely 

 wanting. This area of superficial grey attains its maximum de- 

 velopment immediately ventrally of the level shown in figure 30 

 and is more extensive than in Necturus. 



As in Necturus, there is practically no cerebellar tissue devel- 

 oped in the medial plane except the dorsal commissure. The 

 body of the cerebellum is thin and forms the entire rostral wall of 

 the recessus lateralis and medial wall of its anterior diverticulum. 

 The entire lateral wall of this diverticulum (so far as it is massive) 

 is formed by the anterior lobe of the area acustico-lateralis, which 

 is separated by an ependymal sulcus f i om the posterior lobe (fig. 30) . 

 The differences between these relations and those described 

 above for Nectums are for the most part modifications in the 

 direction of the higher urodeles, as illustrated by Amblystoma, 

 though the cerebellum itself is no larger in Amphiuma than in 

 Necturus. The resemblance to Amblystoma is seen particularly 

 in the membranous roof of the entire recessus lateralis and in the 

 greater concentration of cerebellar tissue in the body. The 

 dorsal portion of the lateral wall of the anterior diverticulum of 

 the lateral recess, which in Necturus is thin but massive, in Am- 

 phiuma is membranous, and the taenia ventriculi quarti is at- 

 tached directly to the area acustico-lateralis in this region as in 

 Amblystoma. 



