466 THE ENTOMOLOGIST. 



exact accordance with the usual order of Nature. Dr. Leach 

 has told us that in all probability every suckler and every bird 

 has its epidermic parasite ; and we find that so far back as the 

 time of Linneus a distinct species of louse had been found 

 respectively on the pig, the Guinea-pig, the camel, the stag, 

 the sheep, the horse, the ass, the mouse, and also on each of 

 the following birds : — vulture, kestrel, buzzard, owl, crow, mag- 

 pie, roller, swan, goose, Muscovy duck, garganey, goosander, 

 petrel, puffin, albatross, tern, spoonbill, heron, crane, golden 

 plover, coot, avocet, peacock, turkey, pheasant, quail, domestic 

 fowl, pigeon, corn bunting, yellowhammer, wagtail, swift, 

 skylark, starling, crossbill, bullfinch, greenfinch, whitethroat, 

 and robin. Four species have been found on man, and four 

 each are said to have occurred on the raven and oyster- 

 catcher. These parasites have received specific names 

 indicative of the genus of suckler or bird on which they 

 depend for subsistence, — an arrangement of great convenience 

 and merit, inasmuch as no species of louse, so far as I am 

 aware, has hitherto been found feeding on two distinct species 

 of animals. The importance of settling this point induced 

 Redi, Degeer, Latreille, Nitzsch, Leach, and Denny, to give 

 the subject their most earnest attention ; and all these authors 

 have investigated this little group of insects with untiring 

 perseverance, thus overcoming in the cause of Science the 

 conventional repugnance to these animals. Mr. Cordeaux, 

 one of the most accomplished of living ornithologists, has 

 done the same ; and I can only regret that the vast amount of 

 information obtained should still remain unpublished. 



These epidermic creatures received at the hands of Latreille 

 the general name of "Parasita;" the name is truthful and 

 very descriptive, but scarcely sufficiently definite or restricted. 

 The group soon became divided into two families : those 

 found on sucklers receiving the Linnean name of Pediculus, 

 or, as a family, Pediculida3 ; and those found on birds being 

 called Nirmus, or, as a family, Nirmidae : this division, 

 however, is not absolute, two of the Nirmidae being attached 

 to quadrupeds ; these are Trichodectes and Gyropus, the 

 former infesting the dog, the latter the badger. 



Regarding, then, these parasites as naturally associated by 

 their parasitic economy, it becomes necessary to consider 

 Avhether they can be incorporated with either of the eight 



