34 



JA'/.Y. 



< i 



f man}- species of Pseudomyrma point to a life in very narrow, tubular 

 branches and twigs. The small Azteca worker is small enough to enter 

 and leave such openings without the great elongation of the head, which 

 in the much larger queen is necessary for the accommodation of the 

 powerful mandihular muscles. The nearly brainless and jawless male 



does not require this adapta- 

 tion. A broad, depressed 

 head points to a life in much 

 flattened cavities (A. hypo- 

 phylla ) , etc. There are, to be 

 sure, other differences in the 

 form of the head (trigona 

 and aurita, both carton- 

 builders ) that cannot be ac- 

 counted for in this way." At 

 least one species of Asteca (A. 

 Z'iridis) is green, a very un- 

 usual color in ants and evi- 

 dently an adaptation to life 

 among living leaves. In Psett- 

 doinynno species the whole 

 body is greatly elongated. 

 These are, in fact, the most 

 slender of ants and anyone 

 who has seen colonies of them 

 filling narrow twigs and stems 

 like so many sardines packed 

 in a box, will be sure to 

 regard the lengthening of the 

 body as an adaptation to life 

 in small tubular cavities. The 

 species of the Old World 

 genus Siina resemble the spe- 



FIG. 174. Carton nest of Asteca muel- 

 leri in the main trunk of Cccropia adenopus ; 

 Santa Catharina, Brazil. From a specimen in 

 the American Museum of Natural History. 

 i ( >riginal.) 



cies of Pseudomyrma very 

 closely in structure and habits. 

 The soldiers of Colobopsis, 

 as I have shown in a former 

 chapter (p. 211) have singularly truncated heads, adapted to fitting 

 into and closing the perfectly circular entrances to the galleries of 

 the nests which are always in wood or m the hollow culms of sedges. 

 Perhaps the soldiers of many species of Cryptocerus and Cataiilacus 

 use their wonderful heads for the same or similar purposes. 



