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188 THE CORRODENTIA. 



toothed mandibles, and witli a pair of softer maxillae 

 furnished with long palpi. This little insect is the 

 Atropos pulsatorius ; it is common in collections_, not 

 only of insects_, but also of dried plants, and may 

 frequently be met with in old books and papers, 

 whence the name of Book-louse is often applied to it. 

 Like the Coleopterous insects of the genus Anobium, 

 it possesses the power of producing a sound like the 

 ticking of a watch, and from this circumstance it has 

 also received the name of the Death-watch, which is 

 perpetuated in its scientific appellation. 



But although this little destroyer of our insect 

 treasures, whose existence puts the entomologist to 

 so much expense for camphor as a bar against his 

 burglarious propensities, is unprovided with wings, 

 this is not the case with the other British species of 

 his family, most of which are furnished, in the perfect 

 state, with four of these organs, traversed by branch- 

 ing veins. The hinder wdngs are smaller than the 

 anterior pair, and when closed the wings lie upon the 

 back in a roof-like form. In other respects their 

 stiiicture is very similar to that of the Atropos pulsa- 

 torius, which their larvse almost exactly resemble, 

 but the tarsi in all stages are only composed of two 

 joints. Several species, such as Psocus binotatus 

 and P. pediculariuSj are found commonly in houses, 

 and their larvse may possibly assist the little Atropos 

 in its attacks upon our collections; but the majority 

 occur about the stumps of trees, old wood, &c. Such 

 are the British species of the Corrodentia, which 

 may, however, be with great propriety separated from 

 the White Ants under the name of Psocina, as they 

 really agree principally with those curious insects in 

 passing their preparatory states in the air, whilst in 



