144 Mr. Eaton on the Ovipositor. 



that the elements of an abdominal segment enter into 

 the composition of the ovipositor. And Mr. Bates in- 

 quired at the April meeting of 1867, whether the ovi- 

 positor was not a modification of an abdominal segment. 

 (See Proc. Ent. Soc. 18G7, p. Ixxxv) . The observations 

 of Mr. Packard, cited above, both invalidate that hypo- 

 thesis and answer this question in the negative. He 

 says that in the semi-pupa stage of the development 

 of Boinhus the elements which go to form the aculeus lie 

 in three separate pairs, and in two groups, in the form of 

 slender non-articulated tubercles, arising on each side 

 of the mesial line of the body. (The elements of the 

 segments from which the components of the aculeus 

 grow out being gradually reduced in size, ultimately 

 become the chitinous basal supports of that organ.) 

 Now where a segment is derived from a pre-existing seg- 

 ment, it is formed by a transverse division of that 

 segment, and not by the coalescence of various out- 

 growths from that segment. Therefore the development 

 of the elements of the Aculeus and the Ovipositor pro- 

 ceeding in a manner different from that of the elements 

 of a segment, those cannot be in any degree homologous 

 with these. 



