NEW FORMICID/E FROM BARRO COLORADO ISLAND. 163 



frequently one of the host workers may be observed in the act of 

 lavishing similar but more elaborate attentions on a Cepobroticus 

 worker. The fungus-grower begins by licking the feet or tarsi, 

 the tibiae and femora, then the thorax or abdomen and finally the 

 head and even the mandibles of the guest. During this operation 

 the latter remains motionless and inclines its body somewhat to 

 one side. 



The Sericomyrmex never feed their guests by regurgitation. 

 This is not surprising because they never feed one another thus, 

 but resort individually to the growing fungus bromatia. When 

 hungry the Cepobroticus workers and queen also crop the fungus 

 mycelium, but they do this rather roughly, using their mandibles 

 and even shaking or disturbing the substratum. The guests very 

 rarely transport or rearrange the particles of the substratum or 

 take the slightest interest in the garden, except as a source of 

 nourishment. Only on one occasion did I see a Cepobroticus 

 carry a particle of the substratum to another spot, insert it and 

 pat it down with her fore feet. When fresh fruit was introduced 

 into the nest, it was much less frequently visited and eaten, by the 

 guests than by their hosts. 



The larvae and pupae of the Cepobroticus can be readily dis- 

 tinguished from the Sericomyrmex brood. The larvae are more 

 slender and more cylindrical and have smaller heads, with flat, 

 3-toothed mandibles. The hairs on the body are more numerous, 

 shorter and stouter, though rapidly tapering at their tips. I was 

 unable to determine whether the larvae are nourished by regurgi- 

 tation or feed directly on the fungus hyphae. The fact that they 

 usually lie in the crypts in small clusters and in less intimate 

 contact with the fungus than the Sericomyrmex larvae would seem 

 to indicate that they are fed by their nurses with regurgitated 

 liquids. 



The inquilines evidently lead a purely hypogaeic life. Only the 

 males and winged females leave the fungus chambers and come to 

 the surface to mate. I took a few of the sexual forms which had 

 thus escaped, and Prof. W. C. Alice, who collected on Barro 

 Colorado Island during the spring of 1924, sent me among a 

 number of miscellaneous ants a few winged females and several 

 males of Cepobroticus which he had evidently taken on the ground 



