416 W. WESCHE ON THE MALE ORGANS OF FLIES. 



slide for study can be made by arranging the parts symmetrically 

 on a slip, after having, in addition to the already mentioned 

 preparation, washed away the glycerine, and kept them in acetic 

 acid for twenty-four hours, followed by one hour in water. Fix 

 each part in its place by the minutest possible drop of white of egg 

 (albumen), heat on a hot plate, dehydrating and adding turpentine, 

 and finally balsam and cover-glass — the chief point being never 

 to let the dissection get dry, or air will get into the cavities. 



Explanation of Plate 22. 



Fig. 1. Diagram of the male organs of Scatophaga liitaria, showing 

 the relative position of the various parts as seen from 

 the ventral side of the insect, {a) Outer plate or 

 forceps inferior, (b) Outer clasper or forceps superior. 

 (c) Inner hook, [d) Palpus, {e) Penis, appendix 

 interna, or adminiculum. (/) Anterior spiny pro- 

 cesses {laminae superiores V) 



2. Inner, smaller hook, x 120. 



3. Plate, X 120. 



4. Exterior, larger hook, x 120. 



5. Inner palpus, x 120. 



6. Penis of S. ster cor aria, x 110. 



„ 7. Internal organ of S. stercoraria, x 125. 



„ 8. Dissection of the genitalia of *S'. lutaria seen laterally, 



the outer plates and hooks having been removed, 



X 78. 

 „ 9. Club-shaped hook in *S'. lutaria, x 120. 



■5> 



Jonrn. Quekett Microicopical Club, Ser. 2, Vol. VIII., No. 52, April 1903. 



