THE CANADIAN ENTOMOLOGIST 225 



indistinguishable. Every collector or hunter knows the value of 

 immobility in concealment. Certainly ever>- collector has felt the 

 impulse to give \oice to some strongly emphatic expletive on losing 

 a coveted specimen which on being approached drew its legs close 

 to its body and dropped to the ground where it remained effectively 

 hidden from his disappointed eyes. We should be careful, how- 

 ever, not to lay too much emphasis on the advantages of this action 

 because it is hardly probable that the natural enemies of these 

 insects are quite as readily outwitted as we are. Indeed the in- 

 stinct may in some animals be not only useless but positively in- 

 jurious. This is true of certain birds which, when pursued, instead 

 of seeking safety in flight or shelter, feign death in the open where 

 they may be easily captured. 



There ha^•e been several explanations given of the nature of 

 the death feint. Certainly there is no consciousness involved, 

 and the instinct is merely a physico-chemical reaction to external 

 stimulus. The most probable theory is that in the death feint 

 we have an example of negative thigmotaxis, that shrinking from 

 contact characteristic of so large a proportion of all classes of ani- 

 mals. 



A NEW NORTH AMERICAN SPECIES OF THE GENUS 

 TETRAMERINX (DIPTERA, ANTHOMYIID/E). 



BY J. R. MALLOCH, URBANA, ILL. 



The genus Tetramerinx belongs to the subfamily Coenosiinae 

 of the Anthomyiidse, and may be distinguished from its allies by 

 the presence of 4 post-sutural dorso-central bristles on the meso- 

 notum. The females are readily distinguished from any allied 

 genus except Phyllogaster by the peculiar clawlike processes on 

 the apical abdominal segment. 



Stein described the genus under the name Tetrachaeta, but 

 this name was preoccupied and subsequently was replaced by 

 Tetramerinx by Berg. 



Key TO Species. 



1. Third antennal joint not over twice as long as 



second (111.) hrevicornis, sp. n. 



July. 1917 



