428 Annals Entomological Society of America [Vol. V, 
at the same time, becoming thinner. The abdominal intestine 
is approximately three times the length of the fly. The thick- 
ened part, 7. e., that nearest the sucking stomach, is the only 
part coiled, and this hes in three simple, superposed coils, 
gradually narrowing to each end. Posterior to this the intestine 
continues, of practically uniform thickness, to the rectum. 
i 
Fig. 3. Stomoxys calcitrans L. Salivary glands and left Malpighian 
tube (semi-diagrammatic). 
The rectum is a transparent sac, cone-shaped, with the 
apex toward the anus. It contains four rectal glands, which 
are long and trumpet like in shape, and terminates in a narrow 
tube leading to the anus. The appendages of the alimentary 
canal are the sucking stomach, the salivary glands, and the 
Malpighian tubes. 
The sucking stomach, when filled with blood, occupies the 
greater part of the abdomen, but when examined before the 
insect has fed, it lies in the anterior third, immediately above 
the salivary glands. Its walls are thin, being composed of a 
single layer of cells with interrupted strands of muscle fibre. 
