MUSCIDiE: THE BLOOD-SUCKING MUSCID^ 167 



"familiar in men's mouths as household words," needs no 

 general preface in a text-book of entomology that is 

 intended for medical officers. Until lately some medical 

 officers were inclined to think that the only species that they 

 need trouble about was Glossina palpalis, the infective agent 

 of sleeping-sickness. The occurrence, however, of cases of 

 sleeping-sickness in circumstances where the agency of G. 

 palpalis seems to be excluded, and the now well-known fact 

 that there are several species of trypanosomes pathogenic 

 to animals that can be carried by more than one species of 

 Glossina are factors that make this easy-going view untenable 

 even for the most unpractical of " practical " men. Moreover, 

 according to Kleine the trypanosome of sleeping-sickness can 

 develop to a certain extent in Glossina morsitans, and 

 according to Koch G. morsitans, G. pallidipes, and G. 

 "fusca " can all be artificially infected with this trypanosome. 



In dealing with the species of Glossina and their distribu- 

 tion Mr E. E. Austen's Handbook of the Tsetse-flies, printed 

 by order of the trustees of the British Museum, 191 1, is here 

 followed, in genuine appreciation of its merits. 



Mr Austen, using characters which are common to both 

 sexes, arranges the species of Glossina in four groups as 

 follows : — 



Synopsis of Groups «?/' Glossina, summarised from Austen. 



All the segments of the tarsus of the hind legs are 

 either entirely or in most of their extent dark 



G. palpalis group. 



Only the last 2 segrflents of the tarsus of the hind 

 legs are conspicuously darker than the other 

 3 segments = 2. 



(Upper surface of abdomen distinctly cross-banded 

 G. morsitans group. 

 Upper surface of abdomen not distinctly banded = 3. 

 (Wings fairly dark ; palpi (except in G. tabaniformis) 

 long and slender G. fusca group. 



Wings pale ; palpi short G. brevipalpis group. 



