THOMISID.^ OF THE AMES REGION 



I. L. RESSLER 



The spiders of the family Thomisidcc are commonly called crah 

 spiders. .They are so-called because of the characteristic crablike 

 attitude in which they hold the legs and because they can walk as 

 readily sidewise or backward as forward. The first two pairs of 

 legs are usually considerably longer and stouter than the third and 

 fourth pairs. The tarsi are two-clawed. The eyes are small and ar- 

 ranged in two rows, both of which are almost always recurved. 



Crab spiders are remarkable for the fact that their color resem- 

 blance is very similar to that of their environment. Many species 

 which live among flowers assume the color of the flower on which 

 they live. Others which live beneath the bark of trees, on unpainted 

 fences and buildings, assume a dirty gray color which enables them 

 to escape the notice, both of their prey and of their natural enemies. 

 The spiders of this family do not build webs or snares, but lurk 

 wherever there may be a place of concealment offered, and from 

 that place pounce upon any unsuspecting prey that may come within 

 their reach. Some crab spiders construct nests or retreats by rolling 

 up or folding the leaves of plants. These nests are lined with silk. 



The Thomisidcc are divided into several subfamilies, two of which, 

 the Misumeninas and the Philodrominae are represented in our 

 fauna. 



Subfamily Misumeninae 



The tarsi of the first and second pairs of legs are never scopulate 

 beneath, but may have a dense covering of hairs. The third and 

 fourth pairs of legs are usually much shorter than the first and sec- 

 ond pairs. The hairs of the body are rod-shaped and stand erect. 

 The upper margin of the furrow of the chelicerse is without teeth. 

 Most of the Thomisida which the writer has collected fall into the 

 various genera of this subfamily. 



Genus MISUMENA 



The spiders of this genus are white or brilliantly colored and 

 are quite large. Both rows of eyes are recurved and the eyes of 

 each row are equidistant from each other. Each eye is set on a 



