162 SUPPLEMENT TO THE ORDERS 



surface of the skin," and Dr. Willan, in a work on cutane- 

 ous diseases, states, respecting the body -louse, that ' ' the nits 

 or eggs, are deposited on the small hairs of the skin, and the 

 animals are found on the skin, or on the linen, and not under 

 the cuticle, as some authors have represented."" The same 

 writer informs us, " that many marvellous stories are related 

 by Korestus, Schenkius and others, respecting lice bred 

 under the skin, and discharged in swarms from abscesses, 

 strumous ulcers, and vesications. The mode in which pedi- 

 culi are generated being now so well ascertained, no credit 

 can be given to these accounts," He thinks, however, that 

 those authors have mistaken some other insects for lice, as 

 some such animals may sometimes be found in putrid 

 ulcers. 



It appears, therefore, that cases of disease from animals 

 residing under the cuticle, cannot be referred to pediculi. 

 The poet Alcman, and Pherecydes Syrius, the philosopher, 

 are mentioned by Aristotle, as having died of some complaint 

 of this kind. But it could not have been a true phthiriasis, 

 as that great philosopher, who attributed it to lice, imagined ; 

 for he tells us, that " they are produced in the flesh, in 

 small pustules, like tumours, which have no pus, and from 

 which, when punctured, they issue." Dr. Heberden, in his 

 Commentaries, informs us of a similar case, which' he terms 

 morbus pedicularis, but which could not be so, for the same 

 reason. He represents the insect as inhabiting tumours, 

 from which, when opened, they issue. He also tells us, that 

 in all respects they resemble the common louse, but in being 

 whiter. But an observer not accurately skilled in entomo- 

 logy, might, as Mr. Kirby remarks, easily mistake an acarus 

 for a. pediculus. 



Dr. Willan has cited two other cases, which he seems to 

 think may with propriety be referred to true phthiriasis. In 

 one of these cases, it is stated that the pediculi so abounded. 



