198 VEHMIN IN THE SKIN. 



Family PEDICULID.E, (LEACH). 



Essential Character. Antennae of five joints, mouth with 

 a fleshy haustellum. 



Natural Character. Apterus, parasitical ; mouth, consist- 

 ing of a fleshy, tubulous, inarticulate haustellum, armed at 

 the extremity with retractile hooks; legs scansorial, tibiae 

 short, thick, armed at the apex on the inner side with a 

 strong tooth, which, together with the large curved tarsus 

 and unguis, forms a claw; tarsus, one jointed, unguis, single; 

 oesophagus, none ; biliary vessels, four, free, equal in length, 

 enlarged towards their extremities. Males with two testicles 

 on each side; females with five ovaries on each side the 

 uterus. Coitus exercitur mare femine submisso. 



Food, the blood of animals. 



Genus H^EMATOPINUS. 



Legs all scansorial; thorax generally narrower than the 

 abdomen, and distinctly separated; abdomen of eight or nine 

 segments. 



Hcematopinus Eurysternus, (Louse of Ox, Fig. 194). 



Chestnut and shining; head, sub-triangular; occiput, 

 rotundate; thorax, transverse, quadrate; abdomen, large; 

 ovate, ashy white; spiraculi, prominent and fascus. Length, 

 1 to !. The young are much more agile than the mature 

 insect, and differ in nothing except a want of proportion, the 

 limbs being much thicker as compared with the bulk of the 

 body, than when adult. 



This parasite is very common on oxen, congregating especi- 

 ally on the mane and shoulders, causing considerable irrita- 

 tion and rubbing, with consequent loss of hair on those 

 parts. 



