4o8 Bulletin American Museum of Natural History. [Vol. XXI ] 



While these latter, however, tend to resemble the normal female in 

 the structure of the thorax but, like normal workers, lack wings, the 

 workers above described have vestiges of wings but show no similarity 

 to the female in the structure of the thorax. They therefore represent 

 a distinct and hitherto apparently unknown group of gynaecoid 

 abnormalities for which I would suggest the name pterergates. 



Postscript. 



While this paper is going through the press I find in a collection 

 of ants made in Isle Royale near the northern shore of Lake Superior 

 and sent me by Dr. Chas. C. Adams of the University of Michigan, 

 three peculiar workers of a new variety of Myrmica rubra sulcinodis 

 Nyl. They resemble one another and approach the female in the 

 structure of the thorax. The mesonotum is delimited anteriorly by 

 a distinct suture, is larger and more convex than that of the normal 

 worker, and has finer longitudinal vngse. There is a small and in- 

 distinct scutellum but no traces of ocelli. Two of the specimens 

 have vestigial fore wings but on the left side only. In one the ves- 

 tige is a minute nodule like that on the left side in one of the M. 

 scabrinodis workers above described (PI. XIV, Fig. 5). In the other 

 the vestige is about the size of those shown in the worker represented 

 in Fig. 4, but more shrivelled. These three abnormal sulcinodis 

 workers resemble a worker of the same species described by Was- 

 mann (Die ergatogynen Formen bei den Ameisen und ihre Erklarung, 

 Biol. Centralbl., XV, No. 16 u. 17, 1895, p. 609) except in possessing 

 wing vestiges. I believe it would be best to regard them all as 

 pseudogynes, although these forms, which are well known in certain 

 Camponotine genera {Formica, Polyergus, and Camponotus) are de- 

 scribed by Wasmann as "stets ungeflugelt" {loco citato, p. 606). 



EXPLANATION OF PLATE XIV. 



Fig. I. — Anterior portion of adult worker larva of Formica rufa showing ini- 

 aginal discs for legs at a, and at b and c vestigial imaginal discs 

 for the hind and fore wings, respectively. After Dewitz. 



Fig. 2. — Thorax and petiole of adult worker pupa of Formica rufa showing 

 vestige of hind wing at b. After Dewitz. 



Fig. 3. — Worker of Myrmica rubra scabrinodis Nylander var. with vestigial 

 fore wings. 



Fig. 4. — Thorax of a second worker of the same ant with more reduced fore 

 wing vestiges. 



Fig. 5. — Thorax of a third worker with still more reduced fore wing vestiges. 



Fig. 6. — Soldier of Cryptocerus aztecus Forel with' vestigial fore wings. 



