Superfamily Argiopoidea 



thoracic slope; under the dorsal eyes there is a white band instead 

 of the three lines, and there is only one white line on each side 

 coming up from the lower margin." 'The female can be dis- 

 tinguished from sylvana only by its smaller size, the slight dif- 

 ferences in the spines of the second tibia and the epigynum" 

 (Peckham). The male measures from .20 to .24 inch in length; 

 the female from .26 to .40 inch. The armature of the chelicera 

 is represented in Figs. 741 and 742. See also the statement 

 on page 664. This species is found in the Gulf States and extends 

 north to Pennsylvania. 



Genus BALLUS (Bal'lus) 



The spiders of this genus are small, short, and stocky, with 

 the abdomen not much larger than the cephalothorax. They 

 jump little, but run over plants and build their sacs under stones 

 and under bark. The following is our only known species. 



Ballus youngii (B. young'i-i). — This spider measures less 

 than one eighth inch in length; it is black, thinly covered with 

 short yellow hairs; on the abdomen the thickening of these hairs 

 form two yellow spots on the anterior part, and three transverse 

 yellow bands. The species has been found in Pennsylvania and 

 Wisconsin. 



Genus SYNEMOSYNA (Sy-nem-o-sy'na) 



This is one of three genera of ant-like spiders that occur in 

 our fauna north of Texas. It is distinguished from Peckhamia 

 by the greater length of the thorax, the quadrangle of eyes oc- 

 cupying only about one third of the length of the cephalothorax; 

 and from Myrmarachne by the form of the hind part of the cepha- 

 lothorax which is narrow, with parallel sides, thus adding to the 

 apparent length of the pedicel. 



The cephalothorax is strongly constricted a short distance 

 behind the posterior eyes but is inflated behind this constriction, 

 so that the middle portion of the thorax is about as high as the 

 head. There is a deep dorsal depression near the middle of the 

 length of the abdomen, opposite which there is usually, but not 

 always, a lateral constriction. 



A single species occurs in our fauna. 



671 



