EN 
proceeds it becomes very marked as may be seen from figures 10 
and 11. Its appearance is probably due to a relative shifting of 
the glottis (forward) and of the articulation of the jaw (backward), 
the marked reduction due to the disappearance of the branchial 
region being a factor. In the adult the furrow has been obliterat- 
ed and in this place the preglottideal tonsil has appeared. Its 
general location has been shown in figure 6, while figure 3 at a 
higher magnification shows the tonsil upon one side only, the level 
being just cephalad of the glottis opening. In the metamorphosed 
salamanders examined, there is considerable variation in position 
and extent, the tonsil being in two (62, 68 mm) distinctly right and 
left, in the remaining five being medial in position. It is the only 

Fig. 12. Fig. 13. 
Fig. 12. The lateral region of gill closure. Salamandra atra. To show the 
thickening of the epithelium and an epithelial remnant in the midst of the connective 
tissue. >< 60. R. Epithelial remnant. 
Fig. 13. The region of the sublingual tonsil. Transform-Salamandra atra. 
Note the epithelial remnant in the connective tissue beneath the epithelium. >< 60, 
KR. Epithelial remnant. 
tonsil recognized in the 51 mm specimen which has just completed 
its metamorphosis. 
The lateral tonsils appear in a region more complicated. The 
closure and obliteration of the gill clefts is completed relatively late 

branchial furrow or cleft. While it is not believed that these furrows are 
homologous, this observation is mentioned without comment in as much as 
tonsillar structures may occupy the site of an obliterated branchial pouch. 
Drüner, L. 1904, found evidence for 7 visceral arches in Amphibia, while 
MaxuscHoK has recently described in Triton, 7 pouches, of which the last (7th) 
developes the lungs, the 6th being rudimentary. 
