78 Bulletin American Museum of Natural History. [Vol. XXIII,. 



This condition is seen in certain Myrmicine genera, especially of the tribe 

 Solenopsidii (Carebara, Erebomi/rma, Diploniorium, 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 sex- 

 ual dimorphism seen in thf great majority of insects and other Metazoa^ 

 This occurs in the parasitic ants of the genera Aner gates, W heeler ia, 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 a condition obtains in certain 

 Myrmicinse (Cremastogaster), Camponotinse (Lasius, Prenolepis, Brachy- 

 myrmex, the North American species of Mynnecocystus), and Dolicho- 

 derinse (Iridomyrmex, 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 America, like Aphcenogaster tennesseen- 

 sis among the Myrmicinse, and among the Camponotinse in the species of 

 the Formica microgyna group {F. difficilis, nevadensis, impexa, montigena, 

 nepticula) . 



8. The female phase disappears completely and is replaced by a fertile, 

 or gynsecoid worker form. This occurs in the Myrmicine Tomognatlnis 

 subloBvis, in certain Ponerine genera like Leptogenys (including the sub- 

 genus Lobopelta), and probably also in Diacamma and Champsomyrmex. 

 The conditions in Acanthostichus and certain Cerapachyi (Parasyscia perin- 

 gueyi) indicate that the dichthadiigynes of the Dorylinae may have arisen 

 from such gynaecoid workers instead of from winged queens. 



9. The female shows a differentiation into two forms (a- and /9-females)' 

 characterized by differences in the structure of the legs and antennse, in 

 pilosity and coloration (Lasius latipes), or in the length of the wings 

 (macropterous and micropterous females of L. niger). The macrocephalic 

 and microcephalic females of Camponotus abdominalis and confusus de- 

 scribed by Emery ^ may also be regarded as a- and /?-forms. In this series 

 of stages, one to five represent changes in the worker caste while the female 

 remains relatively stationary, whereas stages six to nine represent the con- 

 verse conditions. Stages one to four probably succeeded one another in 

 the order given, but stage five may have arisen either from the first or fourth. 

 The sixth to ninth stages must, of course, be supposed to have developed 

 independently of one another. 



1 Le Polymorphisme des Fourmis, etc., loc. cit., pp. 400, 401. 



