258 GLOSSINA PALPALIS [CH. 



Distribution. Glossina palpalis is widely distributed through- 

 out the western equatorial tropical region of Africa. Along 

 the west coast it extends from the Senegal to Angola, where 

 the variety wellmani predominates. Inland it extends as far 

 as Bahr el Ghazal and, according to Brumpt, Lake Rudolf. 

 Proceeding southward the eastern boundary of the species 

 includes the shores of Lake Victoria in British and German 

 East Africa, and Tanganyika together with its rivers. In 

 N.E. Rhodesia the fly is common in the valley of the Luapula 

 River and its southern limit of distribution follows the 

 boundary between N.W. Rhodesia and the Congo, and across 

 Angola to the town of Benguela. G. palpalis has never been 

 found in Nyasaland or the region of Lake Nyasa. 



Internal Anatomy. 



The digestive tract (Fig. 66). The internal anatomy of 

 Glossina palpalis has been carefully described by Minchin, 

 whose account of the digestive tract is closely followed in the 

 present work, with the exception that the term proventriculus 

 is substituted for that of stomach. 



Commencing with the oesophagus (Oes.), this portion of 

 the alimentary canal runs first of all upwards from the pharynx, 

 then bends sharply round and passes backwards through the 

 brain. After bending round, the cesophagus becomes extremely 

 narrow, but gradually widens after passing through the brain. 

 Immediately after entering the thorax it opens ventrally into 

 the proventriculus, a dilatation of the gut which marks the 

 commencement of the digestive region. From the point at 

 which the cesophagus opens into the proventriculus, the duct 

 of the sucking stomach, or crop, begins. 



The intestine arises from the proventriculus about the 

 middle of its dorsal side and runs backwards through the 

 thorax as a straight tube of even calibre until it enters the 

 abdomen, where the intestine swells out into the more strictly 

 digestive portion of the alimentary canal, 



The abdominal intestine is of great length and forms a num- 

 ber of complicated coils, which are represented in Fig. 66. It 

 may be divided into thirteen limbs, for purposes of description, 



