1905.] Wheeler, Vestiges of Wings in Worker Ants. 407 



posteriorly, like the wing-pads in the pupae of normal males and 

 females, and do not stand off at right angles from the thorax as 

 represented, for the sake of clearness, in the figures. The two speci- 

 mens with more considerable vestiges are a trifle larger than the 

 majorit}^ of the workers in the colony, but this, apart from the wings, 

 is the only character in which they approach the female. 



The only other worker ant with wing vestiges in my collection is 

 a soldier of Cryptocerus aztecus Forel taken Dec. 27, 1900, by myself 

 from a normal colony that was living between the leaves of an epiphy- 

 tic Tillandsia near Cuernavaca, Mexico. This specimen (Fig. 6) is 

 in every respect a perfectly normal worker major, or soldier of its 

 species, except that it bears on the external angles of the mesonotum 

 a pair of symmetrical organs representing anterior wings. These are 

 shaped very much like those in the first of the above-described Myr- 

 mica scabrinodis workers. They are .8 mm. long, spatulate, yellowish 

 brown in color, opaque at the base but semi-transparent towards 

 their tips. Their surfaces are transversely wrinkled but hairless. 

 The tegulae, if present, are extremely minute. In the dried specimen 

 the vestiges are directed ventrally and posteriorly like the wing 

 rudiments in the normal female pupae of Myrmicine ants.i 



We must assume that in all the above cases the wing vestiges 

 which, in worker ant larvae, are extremely minute and normally dis- 

 appear in the pupa stage, have, so to speak, been fanned into greater 

 activity of growth by some unusual and unknown stimulus during 

 ontogeny and have persisted till the imaginal stage without, however, 

 attaining to any functional significance. 



The specimens above described not only confirm but emphasize 

 Dewitz's conclusion that worker ants must once have possessed 

 functional wings like those of the existing workers of social bees and 

 wasps. This is evidently only a special case of what Dewitz ex- 

 presses as a general law, now universally accepted by entomologists: 

 "If only one of the sexes of an insect species is winged we must re- 

 gard the wingless condition of the other as acquired during phylo- 

 genetic development." This statement is also clearly applicable to 

 ants, provided we insert the words "one phase of a sex" in the place 

 of "one of the sexes." 



The above-described workers with vestigial wings evidently be- 

 long to the category of abnormal forms intermediate between normal 

 worker and female ants, like the ergatoid females and pseudogynes. 



' This same winged soldier of Cryptocerus aztecus is also briefly described by in\' former impi! 

 Miss Margaret HoUiday in her paper entitled 'A Study of Some Ergatogynic Ants.' Zool. lahrb. 

 Abth. f. Syst., XIX, 4. 1903, p. 315. 



