250 Annals Entomological Society of America [Vol. V, 
median, dorso-ventral slit, which opens into the trachea. The 
prolegs (p/) on the ventral aspect of this segment, are a pair of 
fleshy appendages, which bear on their distal margins a convex, 
double row of black hooks, which point mesad (Fig. 4). 
Eighth Abdominal Segment (Fig. 1).—The last segment of 
the abdomen is somewhat elongated and not so excessively cut 
by transverse furrows as the preceding segments of the abdomen. 
At the middle of the dorsal surface of the.segment, a spine-like 
anal horn (ah) arises. From this point the segment is cut off 
obliquely at an angle of 45°. At the dorsal edge of this sloping 
portion the triangular anal plate (ap) is located. The anus (a) 
is situated ventrad of the anal plate. The anal prolegs (a. pl), 
resemble in most details the prolegs of the fourth abdominal 
segment. However their size is a trifle larger and the relation 
of their connection with the ventral surface of the segment is 
somewhat different. The spiracle (s) of this segment may be 
seen in its usual position. 
B. Internal Anatomy. 
ADIPOSE TISSUE. 
On opening a larva, the first thing noted is the abundance 
of fat, or adipose tissue (Fig. 10). Adipose tissue, as seen 
throughout the body, is the white, flocculent, lobulated, ribbon- 
like material surrounding and adjacent to the various organs in 
the body cavity. This fat tissue is stored up for future meta- 
morphosis. Sections and mounts of adipose tissue stained with 
eosin show (Fig. 10) its oily nature. The large spherical, fat 
cells in their crowded, massed condition assume a polygonal 
form. Internally, the cells are filled with oily globules of fat 
and possess also a dark-staining, centrally located nucleus. To 
rid the larva of this fat, one needs carefully to rub and tease 
it loose. 
ALIMENTARY CANAL, 
Extending from the mouth to the anal opening of the larva, 
there is a long, straight, locally constricted tube, which in the 
abdominal region occupies the greater portion of the body 
cavity. This is the alimentary canal, or digestive tract. On 
opening a larva from the dorsal aspect (Fig. 7), the following 
structures may be observed :— 
Pharynx (Figs. 7, 8, and 18).—The pharynx () is the small- 
est part of the digestive tract and is located at the extreme 
