446 THE NATURAL HISTORY 



self as their historian. As, however, the result of his 

 experience on this occasion might possibly not be so 

 interesting to the general reader as, we doubt not, it 

 was satisfactory to the great naturalist himself, not- 

 withstanding the personal discomfort involved in his 

 course of study, we need not dwell on his discoveries. 

 It will, perhaps, be sufficient to state that, although 

 three known species, if not four, are parasitical on the 

 human subject, the conditions under which they all 

 flourish on the same individual are probably never met 

 with at Harting, and that the species rescued from 

 obscurity by Leeuwhenhoek is the only one that has 

 ever come under our own observation. We have, how- 

 ever, seen many others of the family, for instance, 

 Trichodectes Equi on the horse, Trichodectes longicornis 

 on the deer, Hcematopinus piliferus on the dog, H. Suis 

 on the hog, and the very remarkable Goniodes falci- 

 cornis, formerly known as Ricinus Pavonis, on the 

 peacock. 



Rook pie, which in early spring is esteemed by many 

 as " dainty " a dish as the immortal one celebrated in 

 nursery rhyme, is inseparable in our own experience 

 from very unpleasant recollections of an insect nearly 

 allied to the preceding genera, Nirmus argulus, swarms 

 of which infest the rooklings, and instinctively make 

 their way very expeditiously to the heads of those who 

 are so rash as to handle the birds while yet warm. 

 Many persons appear to be indifferent to the an- 

 noyance caused by these insects, but we have more 

 than once found them exceedingly restless and trouble- 

 some bedfellows, the incessant titillation they occasion 

 in their search for more congenial quarters, effectually 

 " murdering sleep." A similar parasite, Menopon pal- 

 lidum, is still more abundant among the feathers of 

 our common poultry, and another species, the name of 

 which is unknown to us, although, in byegone days of 

 stubble shooting, it has gratuitously afforded us frequent 

 opportunities of identification, infests the partridge. 



