70 THE ROYAL SOCIETY OF CANADA 
EXPLANATION OF PLATES. 
(Lettering common to all figures). 


a — artery. 
ad.t — adenoid tissue. 
bld.c = blood corpuscle. 
bld.s = blood spaces. 
(ee = colloid. 
cap. — capsule. 
ear.b. = carotid body. 
cart. = cartilage. 
e.pb.b. = cells lining vesciles of post branchial body. 
c.t. = connective tissue. 
c.ves. = colloid vesicle. 
e. interves = intervescicular epithelium cells. 
end. = endothelium. 
ep.c = epithelial cells. 
e.ves = epithelium of colloid vesicles. 
je = lumen. 
lic. — lymphoid cells. 
n. — nerve. 
pb.b. = post branchial body. 
p-c. — pigment cells. 
proc.b. — procoracoid body. 
prop.b. = propericardial body. 
pthyr. — parathyroid. 
v. = vein. 
v.pb.b. = vesicles of post branchial body. 
v.b.b. = ventral branchial body. 
DESCRIPTION OF FIGURES. 
Fig. 1.—Diagram showing in ground plan the position of the thyroid, para- 
thyroids, carotid body, ventral branchial body, post branchial body, procoracoid 
body, and propericardial. Their relation is indicated to the hyoid cartilage and the 
principal arterial trunks. 
Fig. 2.—Section through the thyroid body of the frog showing a portion of the 
hyoid cartilage and vesicular and intervesicular substance of the gland. Low power 
drawing. 
Fig. 3.—Section through the ventral branchial body and one parathyroid of a 
frog. The former (v.b.b.) shows the arrangement of epithelial cells in irregular . 
columns with intervening blood spaces (bld.s). In various regions especially at the 
periphery are seen accumulations of lymphatic cells. The latter (pthyr.) consists 
of a solid mass of epithelial cells, some of them arranged in a whorl fashion. Low 
power drawing. 
