J" 



411 



The Male Organs of the Flies Scat op hag a lutaria and 



s. stercoraria. 



By W. Wesche, F.E.M.S. 

 {Read January \Wi, 1903.) 



Plate 22. 



The two species *S'. lutaria and S. stercoraria are common ; they 

 are related to our smaller house-fly, Homalomyia canicularis, but 

 they are predaceous and modified in an interesting manner, 

 having loEger and more setose legs, stronger wings, and more 

 highly developed teeth. 



The genitalia of the male in most of the Muscidae are diflBcult 

 to make out, but in these species, on account of their fair size, 

 their habits, and the larger development of the parts, a little 

 trouble will enable the student to get a clear idea of the armature. 



A dissection of the parts in the cockroach (Blatta orientalis) 

 gives a little help in the study of these flies, and may be briefly 

 referred to. Professor Huxley says* that only numerous figures 

 can make intelligible the position and form of the number of hooks 

 and plates that form these genitalia, " and that though they are of 

 the same nature as the female gonapophyses, they are not their 

 exact homologues." But he does not give the figures or any 

 terminology. 



An interesting text and complete figures will be found in 

 Miall and Denny's work.t But in the matter of terminology 

 there is but little to make use of. However, in Mr. Theobald's 

 volume on British Flies,+ a scheme is given which seems of value ; 

 it is applied to the family of the Mycetophilidae, taking as a type 

 the genus Phronia. The genitalia in this family are of a 

 dififerent character from those usually found in Diptera, and need 



* " Anatomy of Invertebrated Animals," p. 350, 1877 edition, 

 t " The Cockroach," Miall & Denny. 

 % "British Flies," Theobald, p. 126. 



