378 



Phthiracarus americanus, n. sp. (PL XXV., Fig. 14.) 



Pale pinkish brown; integument well chitinized and 

 covered with small pits. 



Cephalothorax twice as long as broad; mandibles very 

 stout and prominent, capable of retraction until invisible; 

 pseudostigmatic organ clavate, of medium length. From each 

 pseudostigma a ridge runs forward along the side of the aspis 

 to its lateral edge. A pair of hairs about two thirds as long as 

 the cephalothorax is situated at its posterior margin, and in 

 front of this pair is a similar one, the hairs about two thirds 

 as long; rostral hairs about two thirds as long as this last pair. 



Abdomen about three fifths as broad as long and very 

 narrow, pointed behind, truncate in front, covered with small 

 pits. The dorsum has four rows of long, slightly curved 

 bristles, about five in each row; and there are four pairs of 

 short, straight bristles on the posterior ventral surface. 



Legs subequal, as long as cephalothorax; claws tridactyle, 

 and half as long as the tarsi; tarsus twice as long as the tibia, 

 and with many long hairs. The tarsus of leg I bears a long 

 tactile bristle half as long again as the tarsus itself; tibia and 

 genual subequal. 



This species differs from Phthiracarus arduus in that the 

 pseudostigmatic organ is much shorter and clavate, while on 

 the side of the aspis there is only one ridge instead of two. 



Length, 0.70 mm.; height, 0.36 mm. 



Under logs and boards. Collected by the writer at Dan- 

 ville, Areola, and Urbana, 111. Many specimens. 



