ANTS AND THEIR GUESTS WASMANN. 471 



Dorylomimus (fig. 27) and especially with Mimanomma (fig. 27a) 

 among the anommatophiles. In these genera no legitimate similarity 

 of coloration bctAveen guest and host exists, because tlie latter pos- 

 sess only rudimentary ocelli (Eciton iwaedator) or have no eyes what- 

 ever {Anomma Wilverthi and A. Sjbstedti). In the guests of such 

 Eciton, liowcver, as have well-developed ocelli there is furthermore 

 added to the tactile mimicry a very exact similarity of coloration of 

 the guest with the same size worker-form of the host, for example 

 in Ecitophya (fig. 28), Ecitomorpha, and Ecitonidia. 



At tlie highest stage of the mimicry t3^i)e, in jVIimanomma, Mime- 

 citon, Dorylomimus and Ecitophya, mimicry even forms the foun- 

 dation for a true guest relation; this has even been established by 

 direct observation for Dorylomimus KoJili (F. Kohl). 



An analogous tactile mimicry to that with the ecitophilous Staphy- 

 liniilse is found also among the ecitopliilous Proctotrypid^ (Hymen- 

 optera) in the genera Mimopria and Ecito])ria. 



The protective type of the New World Eciton guests is represented 

 principally by the genus Xenocephalus (fig. 29), in which the head 

 and the extremities are covered by a protecting roof. Among the 

 Old "World doryline guests we meet an analogous, but less perfect, 

 protective type in Pygostenus and related genera. The highest devel- 

 opment of the protective type of dorylophilous Stapbylinidas, however, 

 is reached in the genus Trilobitideus (fig. 30), standing entirely iso- 

 lated,^ and of which several species live with Dorylus and Anomma; 

 a flat, leaflike form of body fitting closely to the ground, which is 

 furthermore covered with conical humps on the upper surface. When 

 a foraging ant seeks to grasp this guest with her mandibles she can 

 only seize him at one of the humps and at the most hurl him away, 

 if her mandibles do not at once glance off. The insect, in which not 

 even elytra are present, resembles rather a silphid larva than a full- 

 grown beetle. Unfortunately we must here be content with these 

 few examples from the extraordinarily rich field of the adaptational 

 characters of the doryline guests. 



6.— NEST BUILDING AMONG THE ANTS. 



An ants' nest is an irregular system of ])assttges and chambers, 

 which serve as the home of the ants and their l)rood; it is no highly 

 finished structure like the bee comb, and on that account is of no 

 rigid pattern, but capable of an almost unlimited adaptability to the 

 most diverse materials and locations. Beginning with the minute 

 hollow in the earth or crack in the bark, measuring but a few milli- 

 meters, to the large domes of our hill ants and the still more 

 extensive nests of some of the large Atta of America, we find all 



1 Quite recently a new genus, Phyllodinarda, found with Anomma in Kamerun, has proven the 

 affinity of Trilobitideus with the Aleocnarinse. 



