524 



Lieut. F. Tulloch. 



[Feb. 2, 



the ventral surface. From its origin the intestine runs down into the 

 abdomen of the fly as a narrow tube of uniform diameter, until it reaches 

 nearly to the lower border of the sucking stomach. At this point it dilates to 

 several times its former diameter, its wall at the same time becoming thinner. 



The abdominal intestine is proportionately shorter, less coiled, and more 

 distensible than in Glossina ; it is about three times as long as the fly itself. 

 The dilated portion of intestine has three simple coils which lie superposed 

 in the middle part of the abdomen, and then gradually narrows, continuing 

 as a uniformly narrow tube down to the rectum. The narrow lower intestine 

 has variable bends in its course, but is not coiled. 



The rectum (figs. 1 and 2, E.) is a dilated cone-shaped portion of intestine, 

 the apex of the cone being towards the anus. Its walls are transparent, and 

 through them are readily seen four long trumpet-shaped papillae, so-called 

 rectal glands, the narrow ends of which are inserted towards the anus 

 (fig. 2, K.P.). A single trachea enters the base of each " gland." Below the 

 apex of the dilated cone the rectum is continued to the anus as a short 

 narrow tube. In the female this terminal portion of intestine runs within 

 the ovipositor, the anus being situated between the last segment of the 

 ovipositor and the terminal plate. In the male the ejaculatory duct passes 

 over it dorsally from left to right, and runs anteriorly to enter the penis. 



The appendages of the alimentary canal are the Malpighian tubes, the 

 sucking stomach, and the salivary glands. 



The Malpighian tubes (fig. 2, M.T., M.T.) arise from the narrow lower 

 intestine. The proctodaeum, between their origin and the anus, comprises in 

 length about one-fifth of the abdominal intestine. At their point of origin 

 (figs. 1 and 2, 0.) the intestine has a shallow linear constriction. Two tubules 

 arise on each side from a short common tube, and all four tubules are 

 approximately of the same length. The two tubules arising from one side 

 have thickened terminations (fig. 2, T.T.), some four times greater than a 

 salivary gland, and these thickened endings lie in the pericardial sinus. 

 The tubules of the other side are of the same thickness throughout, and 

 their ends lie amid the fat-body of the lower abdomen. Microscopically the 

 tubules are of the usual type. 



The sucking stomach (fig. 1, S.S.) is a thin-walled sac, made up of one layer 

 of flattened cells with occasional strands of unstriped muscle. It ends at 

 the waist in a very fine duct (D.S.S.) which runs up ventrally to the thoracic 

 intestine and enters the proventriculus (P.) immediately .behind the opening 

 of the oesophagus. The alimentary canal and the ducts in the thorax lie 

 in contact with each other in a narrow space between the lateral masses of 

 thoracic muscles. 



