| OCR Text |
Show 258 INSECTA. ORDER III. P ARASIT A( 1 )· The Parasita, so called from their parasitical habits, have but six legs, and are apterous, like the Thysanoura; but their abdomen is destitute of articulated and movable appendages. Their organs of vision consist of but four or two simple eyes; a great portion of their mouth is internal, exhibiting exter· nally either a snout or projecting mammilla containing are. tractile sucker, or two membranous and approximate~ lips with two hooked mandibles. According to Linnrous, they form but one genus, that of PEDICt1Lus, Lin. Their body is flattened, nearly diaphanous, and divided into twelve or eleven distinct segments, three of which belong to the trunk, each bearing one pair of legs. The first of these segments frequently forms a sort of thorax. The stigmata are very distinct. The antennce are short, equal, composed of five joints, and frequently inserted in a notch. There are one or two small ocelli on each side of the head. The legs are short, and terminated by a very stout nail, or two opposing hooks, which enable these animals to cling with great facility to the hairs of Quadt·upcds, or to the feathers of Birds, whose blood they suck, and on whose bodies they propagate and pass their lives. They attach their ova to these cutaneous ap· pendages. They multiply excessively, and one generation succeeds to another with great rapidity. Particular and unknown causes fa~i· Iitate their increase to an astonishing degree in the P. humanus, producing in Man what has been termed the morbus pediculosus, and even in children. These Insects always live on the same Quadrupeds and on the same Birds, or at least on animals of these classes, which have analogous characters and habits. Two species frequently live on the same Bird. Their gait in general is very slow. Some of them-Pediculea, Leach-such as the PEnxouLus, Deg., Or true Lice, have a mouth consisting of a very small tubular mam· (1) Paratita, Lat.-Anoplura, Leach. PARASITA. 259 •111 situated at the anterior extremity of the head, in the form of JDI ut conta•m •m g a sue k er w h en at rest. Tl1 e1. r tars1. are com-a ssneod o'f a joint a1 m ost equa1 m. s1. ze to t h e t1' b't a, termm. ate d b y a ~0 stout nail, folding over a projection and with this point ful- ~ery f 1' T . I . d filling the functions o a .torceps. hose wh1ch have examme resented but two simple eyes, one on each side. P Three speci· es h· ve on M an; t h e.t r ova are terme d m' ta . 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 arc placed, brown or blackish; Jobes of the abdomen rounded. On the head of Man, and of children particular} y. The males of this and the preceding species, at the posterior extt·emity of the abdomen, have a small scaly and conical appendage, resembling a sting, which is probably the organ of generation. Hottentots, Negroes and various Monkeys eat these Pediculi, or are Phthiropagi. Oviedo pt·etends 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 ~ld 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, P!Lthirus, of the P. pubis, L.; Red., Exp., XIX, I, which has a wide rounded body, a very short thot·ax 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., Ill. (2) }'or those species which live on Man, see the splendid work of Alibert on the diseases of the skin. |
