122 GNATS OK MOSQUITOES — CHAl'TEB VII 



be noted, is exactly the same sort of situation in which they 

 were found by Drs. Stephens and Christophers, in Sierra 

 Leone, and there, both these gentlemen and lioss never 

 found them in really dirty water, so that presumably, both 

 An. costalis and funestus, the species concerned, confine 

 themselves to fairly clean water; but, as we have seen, 

 several species can adapt themselves to less nice conditions, 

 so that no generalisation as to the sort of water in which 

 Anopheles larvae will or will not be found is possible, and 

 all attempts to formulate such are simply misleading for 

 the genus, and where recorded, should be accepted exclu- 

 sively for the species to which the observations refer, and 

 to no other. 



How difficult it is to make any definite statement as to 

 the habits of even a single species, may be judged by the 

 fact that even in Italy, where more attention has been 

 devoted to such points than anywhere else, the larvae of 

 one and the same species are stated to be " paludal " in 

 habit by one authority, while the imagines are said to 

 be domestic by another observer. The fact is that it is 

 impossible to lay down any hard and fast rule, and all that 

 can be done at present is to point out the desirability of 

 always recording the exact species referred to, and in noting 

 the habits of either larvae or adults, so that materials for a 

 more complete statement of the case may accumulate in the 

 future. 



The females of, I think I may say, all genera of Mos- 

 quitoes lay their eggs in water. During the past year, a 

 large number of observers have been noting these and 

 kindred points, and no one records any fact that in any 

 way confirms Ross's suggestion that they may sometimes 

 deposit them on the dried-up ground where puddles have 

 previously existed. A gravid gnat must deposit her eggs 

 somewhere, and in such surroundings as the interior of a 

 test tube, which is about the most unsuitable vessel I know 

 of wherein to confine gnats with the view to observe points 

 in their life history ; there is nothing really suggestive of 

 usual habits in her being driven to deposit them on the 

 walls of the tube. 



