Order CORRODENTIA. 



This order is composed of a rather small number of soft-bodied insects with 

 a large head which, while it is not sunken into the prothorax, has no distinct 

 neck. The mouth parts are small, fitted for gnawing, and the antennae are 

 very long and slender. Many are wingless, and these are the "book-lice" 

 which are found in dry, dusty places feeding on starchy materials, gnawing 

 the calendered surface of paper and occasionally damaging museum specimens. 

 They resemble parasites in shape, but run rapidly and have the posterior 

 thighs much enlarged. The winged forms occur on the bark of moss or lichen - 

 covered trees, and are sluggish flyers, preferring to drop when disturbed rather 

 than use their wings The venation of these wings is very peculiar, by the bye, 

 the cells being irregular and the individual veins tortuous in course. 



The wingless forms are mainly referred to the Atropidcc , while the winged 

 forms are in the family Psocidcs. 



Fig. i6. — Psocus lineatus, much enlarged. 

 This represents the forms usually found on tree trunks. 



Family ATROPIDiE. 



HYPBRETBS Hagen. 

 H. tessulatus Hagen. Maine to Kentucky. 



CLOTHILLA Westw. 

 C. pulsatoria Linn. New Brunswick, and probably g. d. 



ATROPOS Leach. 



A. divinatoria Fabr. " New Jersey," Plainfield (U S Ag). This or an allied 

 species is common in houses among books, in dusty drawers, sometimes 

 among linen, where it excites the apprehension of the housekeeper who 



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