766 Wisconsin Academy of Sciences, Arts, and Letters. 
abundant in the gizzard although a few can he seen scattered 
over the entire surface. An exception to this is the posterior 
half of each plate and a little to each side where the projec¬ 
tions are very numerous and form a rectangular area (fig. 18) 
and the spaces between are almost free from the projections. 
Examining a series of transverse sections through the giz¬ 
zard, and restricting what we have to say to that portion bear¬ 
ing the plates, a great difference is noted in the folding of the 
wall in different parts. In the anterior end those portions of 
the wall bearing the plates extend but a little, if any, into 
the lumen of the intestine and are hardly noticeable as folds 
(fig. 19). Passing back the four plate-bearing folds are seen 
to extend further and further towards the center of the section 
until, near the posterior end, the plates nearly touch (fig. 20). 
During this change in the four primary folds the smaller ones 
between them have also increased in size. 
The microscopical structure of the wall of the gizzard is very 
similar throughout. Sections through the plates show the 
cuticular layer to be dark and thick, between the plates it is 
thinner and colorless. In the posterior region, where the four 
folds are well developed, there is generally a space between the 
layer of circular muscles and the hypodermis (fig. 21) but this 
may be due to the separation of the layers in the preserving 
fluid. 
Mid-intestine. This region of the alimentary canal extends 
from the third to the seventh abdominal segment. In external 
view there is a very noticeable annulated appearance, due to 
the alternating ridges and depressions which from any one 
view, extend across the intestine. Such an appearance occurs 
over the entire section of the alimentary canal except for a 
short distance at either end. For 2mm from the posterior 
end the surface is smooth; at the anterior end about 1mm of 
the intestine appears smooth externally, but longitudinal sec¬ 
tions show even this part to be slightly annulated (fig. 22) 
These folds do not all show a regularity in making a complete 
circumference of the intestine or in the distance separating 
them from each other. When, under a strong dissecting lens, 
