603 
in the metamorphosis when the external gills are nearly absorbed, 
while remnants of the branchial structures may persist until the gills 
have quite disappeared. In accordance with extent of the gill pouches, 
the fusions and obliterations are extensive involving the closure of 
the gill slits or openings, the disappearance by fusion and absorption 
of the branchial chamber and the obliteration of the ventral extensions 
of the gill pouches where they run forward in the floor of the pharynx. 
The lateral recess of the pharynx into which the three clefts open, 
becomes obliterated along a line extending from the level of the larynx 
to near the level of the dorsal end of the hyoid (ceratohyale). This 
region of closing is characterized by the marked thickening (piling up) 
of the epithelium particularly at the cephalic end of the seam of 
closure where it projects into the pharynx cavity as an irregular 
papillary ridge or crest (Figure 12). Epithelial remnants from the 
absorbed branchial pouches occur for some time in the midst of the 
connective tissue as irregular tubules or small cysts or groups of cells, 
not only in the lateral region under consideration but in the floor of 
the pharynx, (Br. pouch II, ete.), marking thus places where the epi- 
thelium has been lost by fusion. See also figure 13. 
The histolytic changes at transformation affect the blood and 
blood vessels as well as the epithelial structures that disappear. These 
changes, neither on the histological nor on the morphological side, have 
been followed in as great detail as may be desirable, since it is felt that 
the vascular changes may embody factors of considerable importance 
in the appearance of the tonsils. The blood capillaries immediately 
underlying the epithelium are sometimes caught in the shifting and 
piling up of the epithelium and may become included therein. Blood 
vessels in the connective tissue under the epithelium also appear to 
degenerate together with the erythrocytes contained in them. This 
is particularly true over the hyoid arch in the floor of the pharynx. 
The changes in the connective tissue of the region involved are difficult 
to estimate. 
The lateral tonsils occur in the individual specimens of Salamandra 
atra that were examined in three localities; (a) opposite the inscriptio 
tendinea between the dorsal and ventral portions of the M. cephalo- 
dorso-pharyngeus (83 mm, 1; 70 mm, r.). (b) adjoining the interval 
between the hyoid and the first branchial skeletal arch. (86 mm, 
r.and1.; 68mm, r. and l.; 62mm, r.;60mm,r. and1.). (c) near the dorsal 
end of the depression between the hyoid and the mandible (70 mm, 1.; 
