THE EXTERNAL GENERATIVE ORGANS. 



745 



e. The External Generative Organs of the Female Blow-fly. 



The tubular ovipositor of the Muscidse differs entirely in 

 structure from the ovipositor proper of the Orthoptera, 

 Hymenoptera, and many other Insects. Burmeister [8, p. 194] 

 distinguished it by the term 'vagina tubiformis,' and correctly 

 remarks, ' it is a mere continuation of the abdomen, and con- 

 sists like it of rings, which gradually decrease in compass, so 



A 



Vi. 



Vn. 



FIG. 107. A, The ovipositor of the Blow-fly exserted. in. to viii., sixth to eighth 

 abdominal somites ; a, anal scales ; c, egg. B, Terminal somites of the ovi- 

 positor of a Blow-fly, d, dorsal scale of the anal somite ; st, sternum of the 

 eighth abdominal somite ; s, sternal plate of the anal somite. 



that the largest and most anterior, exactly as in the case of 

 a telescope, receives within it all the rest when this organ is 

 withdrawn within the abdomen, wherein it lies concealed.' 



The Ovipositor consists of four somites. The first of these 

 is the sixth abdominal ring. It exhibits two sclerites, a 

 dorsal and a ventral plate (Fig. 107 A, vi.), and the former, like 

 the corresponding tergum of the male, has two spiracles 

 instead of one at each of its posterior angles. It is united 

 with the annuli both in front and behind by very broad, flexible 



