4 PROCEEDINGS OF THE NATIONAL, MUSEUM. vol.63. 



against the skin. It always clasps a hair, and when coming to the 

 skin thrusts its head to the opening of a hair follicle, holding the 

 hair, clasped all the time with the second and third pairs of legs. 

 The products of the oil glands, which open through the mouths of 

 the hair follicles probably also constitute an important item in the 

 diet of this species. A heavy infestation with this louse apparently 

 causes the hairs to become brittle. * 



No evidence was found indicating that the hairs of the host were 

 eaten or used in any way for food. Specimens mounted on slides, 

 as well as live ones, showed the stomach to be free from any solid 

 bits of hairs. Also, hairs removed from areas of greatest infestation 

 and examined microscopically each showed a normal, tapering tip 

 and no marks of mandibles or mechanical injury in any way. Bird- 

 infesting Mallophaga feed to a considerable extent on the horny, 

 cutaneous growths of the host; in fact, one injurious species is 

 known as the " depluming louse " because it literally eats up most of 

 the feathers on certain heavily infested areas of the host's skin. 

 With the mammal-infesting species it is different, and in the case 

 of the two Gyropid species of the guinea pig no evidence whatever 

 was found indicating that the hairs of the host were used as food. 



It is possible that Gyropids feed to a certain extent upon the 

 blood of the host, yet the skin of a heavily infested guinea pig 

 usually does not show any abrasions. Species of Gliricola with their 

 sticking or cutting apparatus probably feed chiefly, as already stated, 

 on serum as no blood was observed in the bodies of any of the lice 

 of this genus. 



Locomotion. — Most of the Gyropidae have each of the legs of the 

 last two pairs modified into a hair-clasping apparatus (fig. 1). The 

 second segment of the tarsus has become greatly lengthened, trans- 

 versely striated and together with the reduced true tarsal claw, 

 formed into a large, clawlike member which, when the leg is com- 

 pletely flexed, fits into a bootjack type of tenaculum at the base of 

 the femur. This forked tenaculum is striated to match the tarsus, 

 so that, as I have observed in living specimens of G. ovalis, when 

 the latter is pressed between the forks it is held locked. I have 

 observed that when individuals are at rest that they "cast anchor" 

 by locking at least one of the hair-elapsing legs about a hair. 

 Through the binoculars I have studied the locomotion of G. oralis 

 and find that it usually clasps during walking movements at least 

 two hairs. The last two legs on a side work together, usually as the 

 fingers on a single hand, but independently of the opposite legs of 

 the same pairs. G. ovalis never walks backward and, on a smooth 

 surface, is practically helpless. 



In Gliricola porcelli and a few other species the tarsi are greatly 

 reduced and the tarsal claws are wanting. In this species the hair- 



