AND DEVELOPMENT OF C0MY8 INFELIX. 249 



The ovipositor is furnished on either side witli two large expanded chitinous plates ; 

 these are held together anteriorly hy a three-cornered nodule of chitin (PI. 12. fig. 41). 

 Of tliese two pairs of plates, the inner is the larger ; each half carries a fringe of short 

 bristles round the distal border. The outer edge of this plate is strengthened by a 

 thickening of the chitin ; this thickening leaves the margin and turns into the middle 

 of the plate before it reaches the extremity. Where these two inner plates articulate 

 with the triangular nodule, there arises a curved rod which runs round and back, meeting 

 its fellow of the opposite side in the middle line; these two curved bars end near the 

 extremities of the inner plates, and they form the pointed stinging-apparatus of the 

 ovipositor. A little below the level of the articulating nodules, these two carved rods 

 converge together and are embraced by a tliin membranous sheath ; at this point the 

 enveloping sheath expands into a pair of oval claspers or clamps, through which the rods 

 of the sting run. The membrane is continued on as a covering or director to the sting- 

 points. At first I was uncertain as to whether these rods were separate from the 

 membranous sheath or not, but later on I found it was possible to dissect them out as 

 perfectly free structures, grooved to the tip from the point where they become swathed 

 in the sheath. 



As regards the origin of the parts of the ovipositor — or sting — in Hymenoptera, there 



seems to exist a considerable amount of confusion in the literature on the subject ; the 



point on ■which I find authors disagree is as to whether the three pairs of buds (or 



imaginal discs) present in the larval condition belong to two segments or to three. 



Bugnion says they arise in three different segments representing three pairs of 



appendages, and he figures them accordingly ; he says : " la tarlere (gorgeret, stylets et 



valves), representant egalement trois paires d'appeudices, derive de six petits disques qui 



se montrent dans la seconde moitie de la periode larvaire, de ehaque core de la ligne 



m^diane, a la face inferieure des trois derniers segments." ..." J'ai observe moimeme la 



formation des six disques de I'armure genitale chez les larves d'Bnci/rfus, la transformation 



de la partie centrale de ces organes en petits bourgeons digitiformes, puis la division des 



deux bourgeons intermediaii'es en quatre (?), mais il ne ma pas ete possible de suivre leur 



developpement ulterieur." He seems to be in some doubt as to the division of the 



median pair into two pairs of buds. Kraepelin (33), in Apis mellifica, states that in the 



earliest instar " an der Bauchseite der drei vorletzten Segmente findet man um diese Zeit 



je ein Paar langlich rvmder Wiilste, welche, von Tracheen umsponnen und augeosuhein- 



lich der Hypodermis entstanimt, man nach Weissmann's Definition als Imaginalscheiben 



zu bezeichnen das Recht hat." ..." Bald zeigen diese Wiilste weitere Differenzirungen, 



namentlich die des dreizehnten Segmentes. An letzteren gewahrt man nach kurzer Zeit 



eine Langstheilung, derart dass jeder Wulst nunmehr aus zwei nebeneinander liegenden 



cylindrischen Zapfen besteht, deren basale Theile unter sich wie mit dem conespond- 



irenden Wulst der andern Seite verbunden siud. Die Wuclierungen des zwoiften 



Segmentes sind zu langlichen, gekriimrnten Zapfen geworden, wahrend die des elfteii 



Binges zwei ruudiche lait je einem langen I'aden in Verl)iudung stehende Biasen 



repiasentiren." 



31* 



