Mr. Theobald's classification. 



(and culicifacies), and in the other it is pale scaled in the middle 

 (as in listoni). Without entering into details it will suffice to say 

 that we have found varieties of listoni and culicifacies, which present 

 exactly the same markings as Mr. Theobald would have us believe 

 are constant characteristics offunestus and rhodesiensis, and it will 

 therefore be apparent that such characters are insufficient for the 

 separation of these species. 



While we are thus enable to recognise any constant difference 

 between listoni and funestus, except that the former is found in 

 India and the latter in Africa a fact which loses its significance 

 when it is known that several other species of "anopheles" occur in 

 both countries we are also unable to state definitely that culi- 

 cifacies, for example, is a species distinct from listoni. We 

 should be inclined to class these " anopheles " in Wallace's local 

 forms, or geographical races or sub-species ; they are moderately 

 constant and distinct in each locality, but when all the forms from 

 several localities are compared, the differences are seen to be so 

 slight and graduated that it is impossible to define or describe 

 them, though at the same time the extreme forms are sufficiently 

 distinct. 



In view of the difficulties which we have attempted to outline 

 above, we have decided not to adopt any dogmatic opinion as to 

 the distinctness of many of the species of " anopheles," until further 

 study of these insects in their natural state has been made. 



For the same reasons we are unable to accept Mr. Theobald's 

 new classification of "anopheles" into different genera, for not only do 

 the differences between many of the new genera appear to us to be 

 so slight as to be of no more than specific importance, but it has 

 yet to be shown that the shape and arrangement of the scales are 

 constant in the individuals of any given species of mosquito. 

 Darwin has laid it down that " a classification founded on any single 

 character, however important that may be, has always failed ; for 

 no part of the organism is invariably constant," and we think that 

 if a sufficient number of individuals of any species of " anopheles " 

 were examined, considerable variations in the shape and arrangement 

 of the scales would be found. 



The question may also be looked at from the point of view of 

 the worker on tropical diseases. In recent years entomologists 



[63 



