154 IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



the abdomen are dirty white. The legs are thickly covered with 

 small brown spots crowded together near the distal ends. The 

 patella and tibia of the fourth pair of legs have a large dark spot 

 on the upper side. 



This spider ranges throughout a large part of our country. 



Xysticiis formosus Banks. This is a very common spider in the 

 vicinity of Ames. The writer has collected a large number of males 

 and females on low bushes. The females measure about five milli- 

 metres in length and the males about four and one-half millimetres. 

 There is an extremely wide variation in the markings of the two 

 sexes. In the female the cephalothorax is a yellowish brown with 

 three black spots at the posterior end. The lighter central area of 

 the cephalothorax is dark at the posterior end, lighter in front and 

 whitish in the eye region. The abdomen is white, with a dorsal pair 

 of black spots anteriorly and a double row of black spots on each 

 side at the caudal end. 



The male is much darker than the female. The thoracic mark- 

 ings are the same. Several black transverse stripes extend across 

 the caudal end of the abdomen, a pair extend partly across the 

 middle, and a pair of black longitudinal stripes are at the basal end. 

 The ground color of the abdomen is white. The first and second 

 pairs of femora are a uniform brown and the rest of the legs are 

 yellowish. 



This species is widely distributed throughout the United States. 



Subfamily Philodrominae 



The tarsi of the first and second pairs of legs are scopulate be- 

 neath. The third and fourth pairs of legs are as long or nearly as 

 long as the first and second pairs. The hairs of the body are plu- 

 mose and lie flat. The upper margin of the furrow of the cheli- 

 cerae has one or two teeth. Six genera of this subfamily are repre- 

 sented in our fauna, only one of which is represented in the Ames 

 collection. 



Genus PHILODROMUS 



The cephalothorax is as wide as long, and is rounded at the sides. 

 The anterior row of eyes is shorter than the posterior row. The 

 abdomen is flat, longer than wide, and is pointed behind. There is 

 very little difference in size between the two sexes. Most of the 

 members of this genus are protectively colored to resemble their en- 

 vironment. 



