18 J. A. BADERTSCHER 
This area extends through a series of ten consecutive sections 
and is located nearly midway between the two ends of the 
gland. A feature very noticeable in the thyroid of this pig is 
the presence of only a small number of large follicles. These 
are located chiefly near the dorsal border in the caudal fourth of 
the gland. 
Young adult hog no. 1 (fig. 4). The thyroid gland is 26 mm. 
long and its greatest width is 18.5 mm. Its anterior end termi- 
nates in a single blunt point, while its posterior end terminates 
in two blunt processes each about 3.5 mm. long.. The only 
structural feature representing a possible derivative of an ulti- 
mobranchial body is an elongated area of small follicles (fig. 4, 
U.) which extends through 125 consecutive sections. This area 
is located along the dorsal border in the posterior fourth of the 
right lateral half of the thyroid gland and extends for a short 
distance into its right terminal process. More interfollicular con- 
nective tissue is present in this area than in other parts of the 
gland. The anterior two-thirds of the thyroid is free from 
unusually large follicles. Many are found in the posterior third of 
the gland. Two large follicles (C.F.) are represented in figure 4. 
Young adult hog no. 2. The thyroid gland is 29 mm. long 
and its greatest width is 20 mm. The anterior end terminates 
in two blunt processes each 6.5 mm. long, while the posterior end 
terminates in a single blunt point. The only structural feature 
representing a possible remnant of an ultimobranchial body is 
an area of small follicles in the posterior fourth of the left lateral 
half of the thyroid gland. This area extends through a series 
of forty sections and has a structure similar to that of the 
ultimobranchial body represented in figure 4. 
Two areas of large follicles are present. In the interior and 
middle thirds of the thyroid gland these areas extend from the 
tip end of the two anterior processes along the dorsolateral- 
margin of the thyroid. In the caudal third of the gland these 
areas gradually become larger, so that at the extreme caudal 
end they are found throughout the entire thickness of the gland. 
Young adult hog no. 3. The thyroid gland is 26.5 mm. long 
and its greatest width is 20mm. At each end it tapers to a blunt 
