W. WESCHE ON MODIFICATIONS OF LEGS IN DIPTEROUS FLIES. 249 



for possession of the female. This, however, throws Uttle or no 

 light on what I have discussed. 



We have noticed legs used as organs of locomotion ; as arms 

 in grasping or holding prey or mate ; as brushes in cleaning the 

 body and head, and probably as balancers when flying. There 

 yet remains a fifth use : the plumed gnats {Chironomus) use the 

 front legs as feelers, and some of the ordinary gnats {Culicidae) 

 have a habit of holding up the hind legs for the same purpose. 

 As these last three genera are so well known, and present 

 little modification other than that of length and tenuity, I have 

 not figured them. What I have figured may be considered as, 

 in some measure, types of their genera or families, but there 

 remain large numbers of forms equally, if not more, interesting. 



In conclusion, I may be excused for pointing out that the 

 subject of microscopical entomological structure has been much 

 neglected for many years. Naturalists are satisfied with making 

 collections, and the establishment of a new species seems to be 

 the summit of ambition. Personally I feel equally, if not more 

 grateful to that individual who proves a species to be but a 

 variety, or a stage in the life-history of a species. 



There must come a day when further new species will be 

 exceedingly difficult to find, and then the pendulum may swing 

 the other way. and we shall have more study of life-history and 

 of minute structure. Both in the bugs and flies, Hemij^tera and 

 Diptera, there is ample room for original microscopical work of 

 the most interesting nature, and our studies of life -history will 

 be greatly assisted, and have a peculiar pleasure, if we bring to 

 that study a good knowledge of the microscopical structure of 

 the insects under observation. 



Since writing this. Lord Avebury has asked the question, 

 " What is Natural History ? " and answered it in so apposite a 

 manner that I cannot resist adding the weight of his great 

 authority to what I have said. 



" What is Natural History ? The collection of many kinds of 

 animals or plants, the arrangement of specimens in cases, or 

 of insects or dried plants in drawers, is merely a provision of 

 suitable material for study. 



" On the other hand, to study their structure, to understand 

 their relations to one another, to watch their habits, to ascertain 

 their dependence on, and relation to, the forces of Nature, to 



