130 On Flies. [Sess. 



Personally I was of opinion that instead of spending so much 

 money among lawyers, it would have been much more satis- 

 factory to have handed the question over for solution to the 

 Edinburgh Society of Field Naturalists. 



V.— ON FLIES. 

 By Mr P. H. GRIMSHAW, F.E.S. 



(Read Jan. 23, 1895.) 



After some introductory remarks showing how little flies have 

 been studied as compared with the other orders of insects, Mr 

 Grimshaw dealt with the general characteristics of flies, and 

 pointed out in what particulars they differ from other insects. 

 For example, they only possess one pair of wings, from which 

 character the technical name of Diptera is derived ; they have 

 a complete metamorphosis, passing through all the stages of 

 egg, larva, pupa, and imago ; they have piercing and sucking 

 mouth-parts ; and possess a lateral, stalked, suctorial stomach, 

 as in Lepidoptera. The nervous system varies in its degree of 

 concentration : in stout-bodied flies the principal ganglia are 

 fused into one large thoracic mass, while in the slender-bodied 

 species there are three separate thoracic and a chain of five or 

 six abdominal ganglia. The external structure was then de- 

 scribed in greater detail, taking in order the head with its 

 various parts, the different forms of antennte, the shape of the 

 face and structure of the mouth-parts ; the thorax, with its 

 appendages, the legs, wings, and halteres ; and the abdomen, 

 composed of from five to nine segments. The life-history of 

 flies was next dealt with, and attention drawn to the modern 

 method of classification founded upon the nature of the pupa 

 and method of emergence of the imago. 



Mr Grimshaw concluded with a short sketch of the char- 

 acteristics of the principal families, and with remarks on the 

 more remarkable features in the life-history of several well- 

 known species. 



