67 



This is the head-louse so common in the heads of children 

 of the lower classes. It may easily be killed by the appli- 

 cation of calomel. 



Gen. IV. NiRMUS. 



NiRMUS. Hermann., Olfers, Leach. 

 RiciNUS. De Geer, Oliv., Lamarck, Latreille. 



It is now almost fully established, that every species of 

 bird has its own peculiar parasite, no instance having oc- 

 curred, in which one species oi Nirmus has been found on 

 two diifereut birds, although many birds have two or three 

 species peculiar to themselves. The importance therefore 

 of clear descriptions of these animals is so very important 

 to the ornithologist, that it is to be hoped that every natu- 

 ralist who has opportunity to investigate the subject, and to 

 describe the species, will not omit to do so. 



K 2 



