Superfamily Argiopoidea 



Synemosyna formica (S. for-mi'ca). — This is the most common 

 of our ant-like spiders, and the one in which the mimicry is most 



perfect (Fig. 747). It is about 

 one fourth inch in length and 

 very slender. The cephalothorax 

 and basal part of the abdomen 

 is brown; behind the constriction 

 the abdomen is black. There is a 

 pale white spot in front of the 

 constriction of the cephalothorax, 

 and one on each side widening 

 downward under the posterior eyes. 

 There is also a white stripe on the 

 abdomen extending downward from 

 the dorsal depression on each side 

 and uniting in a large white patch 

 underneath. The chelicerae differ 

 in the two sexes; those of the female 

 are cylindrical with the inferior 

 margin of the furrow armed with 

 one tooth subdivided by notches 

 into two or three unequal points 

 (Fig. 744); those of the male are 

 much longer and more angular, and armed on the lower margin 

 of the furrow with a large tooth divided by notches into four 

 unequal points (Fig. 743). 



This species lives on plants and runs like an ant. 



Genus MYRMARACHNE (Myr-ma-rach'ne) 



The genus Myrmarachne is a large one and is widely distrib- 

 uted; but it is doubtful if any species occur in our fauna. It 

 includes ant-like spiders, in which the sternum is long and narrow, 

 and in which the lower margin of the furrow of the chelicerae is 

 armed with five or six teeth. In this genus is placed by the 

 Peckhams the following species although the sternum is wider 

 than is typical of Myrmarachne and the lower margin of the 

 furrow of the chelicerae is armed with a single tooth. It seems to 

 me that the species in question is more closely allied to the tropical 

 genus Zuninga than to this one; but to avoid confusion I leave it 

 where it is placed by the Peckhams. 



Fig. 747. 

 SYNEMOSYNA FORMICA 



C72 



