PARASITA. 259 



nulla situated at the anterior extremity of the head, in the form of 

 a snout, containing a sucker when at rest. Their tarsi are com- 

 posed of a joint almost equal in size to the tibia, terminated by a 

 very stout nail, folding over a projection and with this point ful- 

 filling the functions of a forceps. Those which I have examined 

 presented but two simple eyes, one on each side. 



Three species live on Man; their ova are termed nits. 

 In the two following species, the thorax is very distinct from the 

 abdomen, is about the same width and of a moderate length. They 

 constitute the genus Pediculus properly so called of Leach(l). 



P. humanus corporis, De Geer, Insect., VII, 1, 7. Dirty 

 white; immaculate; emarginations of the abdomen less salient 

 than in the following species. It is exclusively confined to the 

 body of Man, and increases to a frightful extent in the morbus 

 pediculosus. 



P. humanus capitis, De Geer, Insect., VII, 1, 6. Cinereous; 

 the spaces in which the stigmata are placed, brown or blackish; 

 lobes of the abdomen rounded. On the head of Man, and of 

 children particularly. 



The males of this and the preceding species, at the posterior 

 extremity of the abdomen, have a small scaly and conical ap- 

 pendage, resembling u sting, which is probably the organ of 

 generation. 

 Hottentots, Negroes and various Monkeys eat these Pediculi, or 

 are Phthiropagi. Oviedo pretends that these animals abandon the 

 Spanish mariners on their way to India as soon as they have reached 

 the tropics, but that on their return, when they arrive at the same 

 point they find them in possession of their old quarters. It is also 

 said that in India, however filthy be the individual, they are never 

 found except on the head. 



At one period the P. humanus was employed by physicians for 

 the removal of ischuria — they introduced it into the urethra. 



Dr Leach forms a particular genus, Phthirus,o{ the P. pubis, 

 L.J Red., Exp., XIX, l, which has a wide rounded body, a very 

 short thorax almost confounded with the abdomen, and the four 

 posterior feet very stout(2).. It is commonly called Morpion. It 

 attaches itself to the hairs of the genital organs and eye-brows. 

 Its bite is very severe. 

 Redi has rudely figured several other species found on different 



(1) Zool. Miscell, III. 



(2) For those species which live on Man, see the splendid work of Alibert on 

 the diseases of the skin. 



