PARASITA. 357 



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*. 



P. humaiius 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 jjosterior 

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

 pendage, resembling a string, 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 Avay 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 the physicians for 

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



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

 L.; Red., Exp., XIX, 1, which has a wide rounded body, a very 

 short thorax almost confounded with the abdomen, and the four 

 posterior feet very stout f. 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 

 Quadrupeds. That which lives on the Hog has a very narrow thorax 

 with a very wide abdomen, and forms the genus Hcettiatopinus, 

 Leach + ; the Pou du Bujfie, figured by De Geer, Insect., VII, 1,12, 

 presents more important characters. 



The others — Nirmidia, Leach — such as the 



RiciNus, De Geer. — Nirmus, Herm. Leach, 



Have the mouth inferior, and composed externally of two lips and 

 two mandibles, resembling hooks. Their tarsi are very distinct, arti- 

 cidated, and terminated by two equal hooks. 



One single species excepted, that of the Dog, they are all exclu- 



* Zool. Miscell., III. 



•f For those species which live on Man, see the splendid work of Alibert on the 

 diseases of the skin. 



t Zool. Miscell., CXLVI ; P.suis, Panz., Faun. Insect. Germ. LI, xvi, 1. 

 The P. cervi, Panz., lb., xv, belongs to the genus Melophagits, of the Diptera. 



