OF BLOOD-SUCKING INSliCTS AND THE DISEASES THEY TRANSMIT. 299 



Although improbable, it is quite possible that further new species may be 

 found, and to allow for this contiugeucy I have added at the foot of the plate 

 several symbols which could be used in the respective colours if necessary. 



Further it must be noted that observers well acquainted with the genus 

 Glossina but unaccustomed to differentiate the various species often record such 

 under the general term "tsetse." These records obviously could not be included on 

 maps which show only species in detail according to this scheme, but at the same 

 time it is advisable to indicate them for the guidance of others who may visit 

 the same locality and also to show the range of the genus. For these reasons I 

 have added on the plate a symbol in black which could be used to indicate the 

 presence of undetermined species of Glossina. 



I 



