G. C. CRAMPTON 200 



flies (figures 4 and 5) are sometimes called gonopods, but the 

 term gonopod should refer to the entire modified abdominal 

 limb (i.e. it should include the basal segment p of figure 4, as 

 well as the genital style ex, etc.). 



As was described above, the principal parts of the gonitaha 

 of sawflies may be readily compared with those of male ephem- 

 erids, and since the sawflies have retained the primitive con- 

 dition in many respects, they serve to connect the higher insects 

 with the lower ones. Within the sawfly group the following 

 modifications of the general plan shown in figure 5, may take 

 place. The basal plate sp of figure 5 frequently becomes re- 

 duced to a narrow ring, such as the one labeled sp in figures 3 

 and 8, and this basal plate is either atrophied, or it is greatly 

 reduced and may unite with the basal segment of the genital 

 styles in higher insects. 



In the following comparison of the parts of sawflies with 

 higher insects, I shall have occasion to refer to parts which were 

 originally dorsal in certain of these forms, but have become 

 secondarily ventral through a torsion or revolution of the parts 

 about their long axis (through one hundred and eighty degrees). 

 The ol^ject of this revolution through one hundred and eighty 

 degrees is to facilitate mating (see figure 24), and takes place 

 in the male alone, so far as I am aware, I have found such a 

 revolution of the parts in certain male sawflies, and a number of 

 Diptera (and I strongly suspect that a similar condition occurs 

 in the Embiidae, although I cannot prove this as yet). Unless 

 one realizes what has happened in such cases, he is misled into 

 attempting to homologize parts which were originally dorsal and 

 have become ventral only secondarily (through a revolution of 

 the parts about their long axis through one hundred and eighty 

 degrees), with parts which were always ventral and have re- 

 mained so — an error made by Newell, 1018, in the sawflies, and 

 by Brolemann, 1010, in culicid Diptera, etc. I would therefore 

 emphasize the fact that in comparing the sawflies here discussed, 

 with certain of the Diptera, the terms primitive^ dorsal and 

 primitively ventral as applied to the sawflies, etc., refer to the 

 original position of the parts in question, which have become 



TUANS. AM. ENT. SOC, XLVIII. 



