200 VERMIN IN THE SKIX. 



Family PHILOPTERIDJS (BURMEISTEK). 



Essential Character. Antennae filiform, with three or 

 five joints ; maxillary palpi, none ; mouth with strong man- 

 dibles. 



Natural Character. Mouth beneath ; maxillae, none ; 

 mandibulae nearly concealed by the labium; pro-thorax 

 narrower than the head ; meso-thorax none, or hid by the 

 ineta-thorax, which is very large ; abdomen with nine seg- 

 ments ; oesophagus long, unilateral, ending somewhat acutely 

 in the caecum ; biliary vessels, four, free, equal, without any 

 particular enlargement. Males with two testicles on each 

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

 Coitus exercetur mare feminae submisso hijusque pedes 

 tertios tenente antennis, si hae sunt cheliformes. Meta- 

 morphosis indistinct, perhaps none ? 



Genus TEICHODECTES. 



Antennae three-jointed; tarsi with one claw; parasitic 

 upon quadrupeds. Food hair, wool, and the exfoliated 

 particles of the epidermis. 



Trichodectes Equi, (Louse of the Horse, Fig. 199). 



Head and thorax bright chestnut, the former large, trans- 

 versely quadrate ; antennae with the third joint the longest 

 and clavate. Length, 1. 



Common on the horse and ass, especially when fresh from 

 pasture. 



Trichodectes Scalaris, (Louse of the Ox, Fig. 200). 

 Head and thorax bright ferruginous, the former obcordate ; 

 antennae with the third joint the longest and fusiform. 

 Length, }. 



