THE NEST OF AN ANOMALOUS COLONY 
OF THE ARBOREAL ANT CEPHALOTES ATRATUS 
By Neal A. Weber 
Swarthmore College, Swarthmore, Pa. 
One of the distinctive elements of the neotropical ant 
fauna is the heavily armored and spinose genus Cephalotes 
of forested areas. The workers have powerful, short and 
convex mandibles that enable them to gnaw out cavities 
in the trees for nests. Kempf (1951) lists the species 
atratus (L.) from Honduras to Brazil and northern 
Argentina and summarizes the known biological records. 
He has also synonymized quadridens De Geer with atratus. 
As thus known, the worker is characterized as 8 to 14 mm 
and black in color and the female about 20 mm and black. 
The male length is up to 14 mm and with head, thorax 
and penduncle black, gaster and appendages testaceous 
to dark ferruginous. Other characters of the castes are 
fully described by him. 
Under the name of Cephalotes atratus quadridens the 
present colony has been alluded to briefly (Weber, 1938, 
1947 ; Wheeler, 1937 ; Whiting, 1938) and a figure of one 
of the anomalous workers has appeared (Wheeler, 1936). 
No account of its biology or nest has hitherto been pub- 
lished. Observations on the colony were initiated on De- 
cember 11, 1934 and terminated on October 4, 1935, during 
tenure of a National Research Fellowship in Biology. 
It is one of two known ant colonies that contained un- 
precedented numbers of anomalous individuals. Both were 
discovered and observed by the writer in Trinidad, B. W. I. 
and the other ( Acromyrmex octospinosus Reich) was the 
subject of the book by Dr. Wheeler (1937). The Acro- 
myrmex anomalies were considered by him to be mosaics 
or gynandromorphs but were later (Whiting, 1938) ten- 
tatively characterized as intersexes and intercastes. Dr. 
Whiting suggested that the Cephalotes anomalies, called 
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