20 NEUROPTERA, 



Not unfrequently the excrements are found adhering, in the 

 shape of little black lumps, to the wings ; these were for- 

 merly erroneously supposed to be eggs. In certain respects 

 some of the species live parasitically in the productions of 

 various species of Cynips; thus I have reared P.soci from 

 the well known bedeguar of the willow, and from the galls 

 of Teraa terminalis. Several species of Clothilla are myr- 

 mecophilous. 



The number of species of Psocidce is apparently very 

 great, although scarcely more than a hundred are described ; 

 too little regard has been paid to the diminutive creatures. 

 Mr. Nietner found about thirty species in the immediate 

 vicinity of his residence at Rambodde, in Ceylon, and it is 

 to be presumed that a considerable number of species are 

 everywhere to be taken ; more especially as the Psocidm 

 endure every climate, and have been detected in Greenland 

 as well as beneath the equator, and different plants, as in 

 Ajjhis, haibour distinct species. Even the European species 

 are imperfectly known ; I have described upwards of thirty 

 species from America ; from other parts of the world few are 

 known. I possess more than eighty species. 



The determination of the species is necessarily rendered 

 difficult by their shrivelling up after death, and the variations 

 in colour of the living ci'eatures. The best characters are 

 derived from the form of the head and antenna}, the pro- 

 portions of the eyes, the wings and their veins, especially the 

 form of the pterostigma and the posterior marginal cell, and 

 lastly the colour and markings of the head and wings. The 

 sexual organs will also probably afford good characters, but 

 hitherto these parts have not been very carefully inves- 

 tigated. 



The family Psocidce is a pre-eminently worthy subject for 

 a monograph, and besides numerous new species will present 



