NO. 2 ENCYCLOPEDIA OF INSECT ANATOMY — SNODGRASS 43 



An outgrowing genital process is in general a gonapophysis, a 

 term applicable to the male as well as to the female. Specifically the 

 prongs of the ovipositor are called the valvulae and the supporting 

 plates the valvifers (valve carriers). The word valva in Latin was 

 the name for one of a pair of folding doors ; in modern mechanics a 

 valve is a device for shutting off the flow of gas or water through a 

 pipe, and in anatomy a valve is a fold in a blood vessel or the heart 

 wall that regulates the flow of blood. Clearly, then, the use of the 

 term valves, or the dimunitive valvulae, for the prongs of the insect 

 ovipositor has no justification from the original meaning of the word. 

 The ovipositor is not a closing apparatus but a conducting organ. 

 However, since we cannot well describe objects or anatomical parts 

 without having names for them, the terms valvulae and valvifers 

 will be used in the following description for the lack of appropriate 

 substitutes. 



In the typical pterygote ovipositor the free part of the organ is 

 usually a tapering shaft composed of the first and second valvulae 

 which enclose a narrow passageway for the eggs discharged from the 

 opening of the oviduct between their bases. The ventral first valvulae 

 slide back and forth on the second valvulae by interlocking ridges 

 and grooves, and the second valvulae have a similar movement of 

 their own alternating with that of the first valvulae. The movements 

 of the valvulae are produced by muscles of the supporting valvifers, 

 since the valvulae arise from the anterior ventral angles of their re- 

 spective valvifers. The second valvifers are rocked on the lower 

 edges, or sometimes on pivots, of the ninth tergum by strong antago- 

 nistic anterior and posterior muscles arising dorsally on the tergum. 

 This imparts a back-and- forth movement to the second valvulae, 

 which often united, giving a stronger support for the first valvulae. 

 The first valvifers are small plates articulated on the anterior ends 

 of the second valvifers, and each is provided with a muscle from 

 the eighth tergum. The up-and-down movements of the first valvi- 

 fers give a back-and- forth movement to the first valvulae on the 

 second valvulae. The movements of the valvulae on each other carry 

 the eggs through the channel of the ovipositor. The so-called third 

 valvulae, when present, are usually either slender styluslike processes 

 projecting from the rear ends of the second valvifers, or flat lobes 

 that ensheath the distal end of the ovipositor shaft, but in some 

 Orthoptera they are broad lateral plates of the shaft. 



There are, of course, many variations in the size and shape of the 

 ovipositor in the several orders of pterygote insects, but the gen- 

 eral structure and mechanism of the organ are essentially the same 



