iQoS] The Polymorphism of Ants 59 



3 . The worker becomes dimorphic through the disappearance 

 of the desmergates, so that the originally single variable caste is 

 now represented by two, the soldier (dinergate) and worker 

 proper. We find this condition in certain Myrmicinse and Cam- 

 ponotinffi (Cryptocerus, Pheidole, Acanthomyrmex, Colobopsis, 

 etc.) 



4. The soldier of the preceding stage disappears completely, 

 so that the worker caste again becomes monomorphic, but is 

 represented by individuals very much smaller than the female. 

 Such individuals are really. micrergates. This condition is seen 

 in certain Myrmicine genera, especially of the tribe Solenopsidii 

 (Carebara, Erebomyrma, Diplomorium, most species of Solenop- 

 sis, etc.) 



5. The worker form disappears completely leaving only the 

 males and females to represent the species, which thus returns to 

 the condition of sexual dimorphism seen in the great majority 

 of insects and other Metazoa. This occurs in the parasitic ants 

 of the genera Anergates, Wheeleriella, Epoecus, Sympheidole and 

 Epipheidole. 



6. In certain species the workers remain stationary while the 

 female increases in size. This is indicated by the fact that the 

 worker and male have approximately the same stature. Such 

 conditions obtain in certain Myrmicinse (Cremastogaster) , Cam- 

 ponotin^ (Lasius, Prenolepis, Brachymyrmex, the North Amer- 

 ican species of Myrmecocystus) , and Dolichoderinae (Iridomyr- 

 mex, Dorymyrmex, Liometopum). 



7. The worker caste remains stationary while the female 

 diminishes in size till it may become even smaller than the large 

 workers. This occurs in certain parasitic species of North Amer- 

 ica, like Aphaenogaster tennesseensis among the Myrmicina?, and 

 among the Camponotinas in the species of the Formica microgyna 

 group (F. difficilis, nevadensis, impexa, dakotensis, nepticula). 



8. The female phase disappears completely and is replaced 

 by a fertile, or gynsecoid worker form. This occurs in certain 

 Ponerine genera like Leptogenys (including the subgenus Lobo- 

 pelta), and probably also in Diacamma and Champsomyrmex. 

 The conditions in Acanthostichus and certain Cerapachyi (Para- 

 syscia peringueyi) indicate that the dichthadiigynes of the Dory- 

 lina? may have arisen from such gynaecoid workers instead of from 

 winged queens. 



