SUPPLEMENT TO THE ORDERS, 



Thysanoura, Parasita and Suctoria. 



Notwithstanding that we have thus grouped these orders 

 together, in consequence of the scantiness of the materials 

 which they present for our supplementary observations, we 

 shall not find a great deal to say in addition to the excel- 

 lent descriptions in the text. 



As to the first, we must pass it over altogether, for we 

 could say nothing concerning it, except in relation to the 

 quick movements, and the localities of the animals which 

 compose it, which have been already mentioned in the text. 

 We shall pass on, therefore, at once, to the consideration of 

 those parasitic animals with which, unfortunately, our own 

 species is but too closely connected. 



All LICE live on blood, some on that of man, others on 

 that of quadrupeds. They suck it with their proboscis, 

 which is hardly ever perceived, unless it be in action. There 

 is no quadruped which has not its particular louse, and some 



