the Ovipositor. 143 



parts of the, in some degree, homologous organ of the 

 IclinewnionidcB. According to Mr. Packard,* during the 

 semi-pupa stage of the development of Bombus, the first 

 two pairs of elements arise in juxta-position fi'om the 

 eighth abdominal ring; whilst the third pair is given off 

 from the apical edge of the ninth ring : and at this 

 period they are in the foi^m of slender non-articulated 

 tubercles. The two outer pairs ultimately ensheath the 

 inner pair completely. From this it appears that the 

 spiculge filamentosfe {ennato-tergo-rhahdites or stylets, 

 Lac.-Duth.), which lie in the groove of the acus {gorgcret 

 or ennato-stermte, Lac.-Duth.), homologize specially with 

 the terebral elements oi Agrion. Unfortunately it is not 

 stated in the Annals of Natural History {Joe. cit.) what 

 becomes of the remaining pairs of elements : so that 

 whether they become anchylosed together so as to form 

 the acus (an event not altogether incompatible with its 

 anatomy), or whether, on the other hand, the second 

 pair cohere to form the acus, and the third pair maintain 

 their distinctness under the form of the ovipositor, is 

 a matter of uncertainty. On the earliest opportunity 

 I will make the observations necessary for the decision 

 of this question. Meanwhile it is clear that neither of 

 them is specially homologous with any of the elements 

 of the ovipositor of Agrion, and that the third pair of 

 elements presents the same general homology as the 

 terebra, whether it forms a part of the acus, or whether 

 (as I am inclined rather to believe) it is the ovipositor. 



In short it may be regarded as certain that the Acu- 

 leus of Hymenoptera and the Ovipositor of Agrion have 

 very little in common with one another. Indeed so dif- 

 ferent are they that it might almost be regarded as an 

 impropriety of language to say that the one is a modi- 

 fication of the other. The number indeed of their com- 

 ponents is identical, but in scarcely anything besides 

 the number of their constituents can it be said with 

 M. Lacaze-Duthiers that " les tarieres des Nevropthrcs sent 

 semhlahles aux tarieres des Hymenopthres.'' — (Ann. Sc. 

 Nat. Fr. 1853, tom. xix. p. 30) . 



In his elaborate and most valuable '' Recherches sur 

 TArmure Genitale Femelle des Insectes," (Ann. Sc. Nat.Fr. 

 1849-1853), the author just named upheld the hypothesis 



* Au abstract of Mr. A. S. Packard's paper, On the Development and 

 Position of the Hijmenoptera, is given in Ann. and Mag. Nat. Hist., 3rd 

 ser., vol. xviii. p. 82, et seq. 



