1930] Subaptery and Aptery in Genus Monomorium 203 
Before proceeding to the description of this condition 
of subaptery, it should be noted that an extremely unusual 
condition of aptery has long been recognized in Mono- 
morium. In Monomorium floricola, M. carbonarium subsp. 
ebeninum and M. minutum subsp. ergatogyna Dr. Wheeler 
(1905) observed that the females had a thoracic structure 
typical of winged forms, yet they showed no indication of 
ever having borne wings. Thus we have a case of aptery 
unaccompanied by the usual fusion of sclerites and by huge 
diminution in size of the thorax. Forel describes M. andrei 
of Oran as having both winged and ergatoid females as 
well as the Indian M. shurri and M. dichroum, but as he 
fails to explain the thoracic structure of the ergatoid and 
the winged female, it is impossible to judge whether the 
apterous condition here is similar to the case cited by Dr. 
Wheeler. 
In two Australian species, M. rothsteini and M. ( Noto - 
myrmex) subapterum , the males show no differences in 
the size and development of the wings, which in both 
species are large and of the usual structure, but the females 
exhibit differences in the size of the thorax and wings. The 
wing of rothsteini measures 6.8-7 mm., while that of sub- 
apterum is only 3 mm., and its thorax is also much reduced 
in size. A somewhat similar case was found in the female 
of the related species M. ( Notomyrmex ) rubriceps. In a 
specimen of an incompletely dealated female the size of 
the remaining hind wing indicated that all the wings were 
very much reduced previous to deflation, and probably 
represented a more advanced condition of subaptery than 
the female of subapterum. It should be noted that in the 
case of subapterum several specimens of the female were 
available for study, each exhibiting the subapterous con- 
dition of the wing. In the case of rubriceps only a single 
specimen of the female illustrates the subapterous condi- 
tion, while in five other specimens from the same nest all 
the intermediate stages between the subapterous and the 
apterous condition are represented. In the case of sub- 
apterum the condition of subaptery is evidently normal, 
while in rubriceps it is, perhaps, abnormal. However, 
whatever the case may be, the female of rubriceps repre- 
