No. 637] 



PARASITISM 



145 



and in Sphcsropyx (Cusliman, '13), in a fewlclmeumonidae 

 (e.g., species of Cryptus) and in a few BetliylidcT, it would 

 seem likely that they also are polyembryonic. 



The widespread occurrence of germinogony and its 

 apparently erratic distribution show that it can be of no 

 general taxonomic interest at least as an aid to classifi- 

 cation. It is indeed quite the opposite, for the develop- 

 ment of the egg in the process of fragmentation is so 

 similar in the Chalcidoid and Serphoid that wo might be 

 led to believe it of common origin. As their ancestors 

 were undoubtedly not polyembryonic, such eaii not be llie 

 ease and the process must have originated indcijcndcntly, 

 just as it has in several totally unrelated animals like 

 certain annelids {e.g., Helodrilus) which exhibit it in an 

 imperfect condition (Weber, '17) and in the armadillo 

 (Newman and Patterson, '10) among mammals where it 

 has become completely established. A quite similar 

 modification of development is seen in the formation of 

 the rediae in the sporocysts of Distomes. Still similar, 

 but delayed until the larval stage, is the process of paedo- 

 genetic multiplication in the Cecidomiid fly Miastor 

 (c/. Felt. 'in. w(>]l known to all entomologists. 



It appears I'l-oni an\' uvneral survey of the habits of 

 the i)arasitie 1 lynienoptera that we find certain taxonomic 

 groups of host commonly attacked by discrete groups of 

 closely related parasites. It is natural that such combi- 

 nations should impel our attention, as they may be fitted 

 with the least etfort into a classified scheme, and further- 

 more their mere recurrence is sufficient to indicate that 

 they are not due merely to chance. 



The following list includes a few striking instances of 

 this sort drawm at random from widely separate sections 

 of the order: 



Families 



.Alysiidae Diptt-ron 

 Trigonalida? \espida\ 



