PLATE 1 
EXPLANATION OF FIGURES 
la, 2a, and 3a Drawings to show typical stages in the development of Bufo 
lentiginosus. Figure la represents stage I. Figure 2a represents stage III. 
Figure 3a represents stage VI. All drawn to scale and magnified X 3. 
1b, 2b, and 3b Drawings to show transverse sections of the thyreoid glands of 
la, 2a, and 3a, respectively. Figure 1b, transverse section of the thyreoid gland 
of la. Figure 2b, transverse section of the thyreoid gland of 2a. Figure 3b, 
transverse section of the thyreoid gland of 3a. All drawn to scale and magnified 
X 75. 
4, 5, and 6 Whole mounts of the thyreoid glands of the stages represented 
above. Figure 4, whole mount of thyreoids of I b. Figure 5, whole mount of 
thyreoids of II h. These thyreoids have a volume almost identical with the 
average in group III. Figure 6, whole mount of thyreoids of VI f. All drawn 
to scale and magnified. 
