XVI PREFACE. 



A difference of opinion appears to have existed amongst 

 Entomologists, as to whether the Pediculidae and Nirmidae, 

 undergo any metamorphoses. The late distinguished Pro- 

 fessor Nitzsch, who had paid more attention to the History 

 of the Epizoica than perhaps any other Zoologist of the 

 present day, in his paper on the families and genera of 

 animal insects,* says " Metamorphosis indistincta sub- 

 nulla, (larva pupaque agili, currente, vorante, imagini per- 

 simili)." Our own talented country man, the late Dr. Leach, 

 who had also attended to the economy of this tribe, and 

 contemplated publishing upon them, was satisfied they 

 underwent no change, at least not such as we consider 

 metamorphosis. Hence he placed th m in his sub-class 

 Ametabolia (insects undergoing no metamorphosis), while 

 Dr. Burmeister, whom I consider the first authority for this 

 tribe of insects, arranges them under his sub-class Hemi- 

 metabola. ("Insects with an imperfect metamorphosis, 

 i. e. larva, pupa, and perfect insect, strongly resembling 

 each other, the pupa possessing locomotion and eating." ) 

 This last I consider the most correct view which can be 

 taken, for although there is not a metamorphosis as in the 

 more persect insects, consisting of larva, pupae, and imago, 

 widely differing from each other in general appearance, 

 habits, and functions ; yet a series of semi-transformations 

 takes place in the shedding of the skin a definite number of 

 times, by which the individual acquires a greater symmetry 

 of form and appearance, and most probably a greater perfec- 

 tion of parts or organs ; though the latter may not be so 

 evident to our sight as in the former. Having obtained 

 several nits or ova of Hcematopinus, Eurysternus, and Suis, 

 and placed the same in a quill which I carried in my waist- 

 coat pocket, from the warmth they thus received I soon 

 became sole proprietor of a family of my young friends. 

 These I examined soon after their exit from the ova, but 



* Die Farnilien und Gattungen der Thierinsekten, Von Dr. C. L. Nitzsch. 

 Germar's Magazin def Entomologie, iii. pp. 261, 31G. 



