394 C. H. TURNER 



that this fauna had a long period of quiet development and be- 

 came very extensive. The miocene fossils perhaps represent 

 this fauna." (4) Genera and derivatives representing the hol- 

 arctic fauna forced southward by the advance of the ice-sheet. 

 These are the forms that show the relationship of our insect 

 fauna to that of northern and middle Europe. The bulk of 

 many large families belong here. (5) Genera representing a 

 comparatively recent influx from the American tropics, a migra- 

 tion still in progress. He gives examples of all of these elements 

 and closes his article with: " I doubt not but there are other 

 elements also in our fauna ; but I think these are the most notice- 

 able, and sufficient to show that the Nearctic insect fauna is 

 not a realm, but a conglomeration of several such realms." 



LETISIMULATION 



Chapman (23) states that when touched the adult Agrilus 

 bilineatus letisimulates and drops to the ground. 



According to Essenberg (34) death feigning is a characteristic 

 of the water-strider. It crosses its forelegs and becomes per- 

 fectly rigid. 



Turner (119) finds that the ant-lion letisimulates so perfectly 

 that one can cut off the tips of its legs and even of its mandibles 

 without inducing a response. All death-feigning poses are not 

 death attitudes. ' In the ant-lion letisimulation seems to be 

 but an exaggeration and prolongation of the pause made by 

 most animals when they are startled. The total behavior of 

 the death-feigning ant-lion supports Holmes's contention that 

 ' the instinct of death-feigning is connected with much that is 

 called hypnotic in the lower animals,' and endorses James, when 

 he says: ' It is really no feigning of death at all and requires 

 no self-command. It is simply terror paralysis which has become 

 so useful as to become hereditary.' " 



MISCELLANEOUS ACTIVITIES 



Commensalism. Diguet (31) describes a case of commensalism 

 between a spider and a beetle and another species of spider and 

 ants. The beetles and ants seem to remove the remains of the 

 numerous flies that become ensnared in the web. 



Knab (70) records a case of commensalism in Desmometropa. 



Disease Spreading Activities. Articles on the relation of flies 



