44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I46 



in all. Insects that possess this type of ovipositor are able to deposit 

 their eggs in the ground, to insert them into the stems and twigs of 

 trees, or into the bodies of other insects. The ovipositor of some 

 Odonata is a well-developed piercing organ by which the female 

 inserts her eggs into the stems of underwater plants. In other 

 Odonata the ovipositor has become greatly reduced and nonfunc- 

 tional ; such species merely drop their eggs on the water during flight. 

 In the wasps and the bees the ovipositor has been remodeled into a 

 stinging organ for the injection of poison from glands opening into 

 its base. The eggs of these insects are discharged directly from the 

 opening of the oviduct at the base of the sting. 



Theoretically the ovipositor has been interpreted as a development 

 from primitive legs of the eighth and ninth abdominal segments. 

 The valvifers are supposed to be the coxae, the first and second 

 valvulae to be coxal outgrowths, or gonapophyses, and the third 

 valvulae perhaps coxal styli of the second valvifers. Superficially 

 this interpretation looks plausible since the valvifers are moved by 

 muscles arising on the terga of their respective segments, and a com- 

 parison with the simple ovipositor of Thysanura at first sight appears 

 to bear out the suggested homologies. The two long slender gona- 

 pophyses of each genital segment of the Thysanura appear to arise 

 from the anterior mesal angles of the stylus-bearing coxal plates. 

 However, they are only closely attached to these plates, and their 

 basal muscles arise on the sternal area or a sternal plate between 

 them. The gonapophyses have no musculature from the coxal plates, 

 as they should have if they are either telopodites of the limbs or 

 gonapophyses of the coxae. 



Matsuda (1957, 1958) has given a critical historical review of 

 work on the structure of the insect ovipositor and of opinions that 

 have been held on the homologies of its parts. Among the earlier 

 writers, Heymons (1899 and earlier papers) was the foremost 

 proponent of the concept that the gonapophyses (prongs of the ovi- 

 positor) are secondary ectodermal outgrowths of the eighth and ninth 

 abdominal sterna in no way related to the transient embryonic limb 

 vestiges on the other segments of pterygote insects, or to the stylus- 

 bearing coxal plates of Thysanura. Tillyard (1917) notes that in 

 the Odonata the rudiments of the ovipositor develop early in the 

 larval life, "but have nothing to do with the primitive paired seg- 

 mental appendages of the abdomen, which are lost during embryonic 

 life." On the contrary, most subsequent writers down to the present 

 time have held to the theory that the oviposior represents a pair of 

 abdominal limbs of which the valvifers are the coxae. From a com- 



