PREFACE. 



During the year 1827, three or four specimens of Pavo 

 cristatus having passed through my hands, upon each of 

 which I observed for the first time, several examples of the 

 large and well marked parasite of this bird, the Goniodes 

 falcicornis, I was induced to examine whatever other species 

 of birds, &c. might come in my way, to ascertain whether great 

 diversity in size or appearance existed between the parasites 

 of different species or genera. This I soon found to be so 

 considerable, that I resolved upon forming a collection, and 

 ascertaining what was written upon the parasitic tribes. 



In the prosecution of the former part of the task I found 

 little difficulty, but with respect to the latter, I could make 

 no progress, as no distinct treatises upon the families were 

 in existence, and all that was available were either mere 

 enumerations, without reference or figures, or occasional 

 descriptions of species which were scattered through various 

 w r orks, many of which were not easy to procure, especially 

 in provincial towns, where, in the majority of cases, works 

 on Natural History are only sparingly to be found. I 

 therefore proposed to myself the illustration of the Pedi- 

 culidce and NirmidcB^ under a conviction, that a work ex- 

 clusively devoted to these families, concentrating all that 

 was known, with figures of the species, however imperfectly 

 it might be executed, was a desideratum to the Entomo- 

 logical Literature of this country. Upon communicating 

 these views to my learned friend William Sharp Mac Leay, 

 Esq., he strongly urged me to proceed, and promised all 

 the assistance his own extensive knowledge of Entomology 

 enabled him to give, as well as that assistance which his 

 friendship could secure from other distinguished individuals. 

 With such promises of aid I could no longer delay the com- 

 mencement, and carrying on this essay to its completion, 

 which, however, has greatly exceeded the limits I had cal- 

 culated upon at the outset; still it is most probable many 

 species remain unrecorded, as several of the rarer, and some 



