ART. 20. STUDIES OF THE BITING LICE EWING. 3 



either two, three, or four segmented; the antennae four-segmented, 

 but frequently appearing three-segmented ; the head with broad deep 

 antennal fossae and the temporal region rounded. 



HABITS. 



Observations on habits were confined to the two species, Gyropus 

 ovalis Nitzscli and Gliricola porcelU (Linnaeus), occurring on the 

 guinea pig. A young, white guinea pig, infested with l)oth these 

 species was obtained and by constant handling and training was 

 brought to such a state of confidence and contentment that it would 

 rest on the stage of a binocular microscope for long periods while 

 observations were being made on the louse species it harbored. The 

 white hair greatly aided both in locating and in following the lice 

 through the fur. During this process the fur would be parted re- 

 peatedly by the use of a comb or forceps. Lice also were removed 

 both with and without some of the hairs of the host for observation 

 with the higher powers of the compound microscope. 



Food. — No definite conclusion »ould be drawn from the observa- 

 tions made on food habits. That the food of both these species con- 

 sists in part of cutaneous secretions and excretions and in the case 

 of G. porceUi of serum in addition, is indicated by several observa- 

 tions. First, it was noticed that both louse species remained prac- 

 tically all the time next to the skin. Notwithstanding the guinea 

 pig was heavily infested with lice, the latter were seldom noticed 

 except when the fur was parted. Again, a combing with a fine- 

 toothed comb, such as is used to remove the head lice of man, only 

 brought to the surface two individuals. Wlien observed resting 

 both species of lice held their heads against the skin of the host. 

 Further, the eggs were invariably laid at the bases of the hairs, and 

 almost always only a single one to a hair. 



Mjoberg was the first one to demonstrate in G. porceUi a type of 

 lancing mouth parts. The lancing or sticking apparatus was no 

 other than the outer hypopharyngeal chitinization. In a related 

 species this chitinization (fig. 14) is provided with two anterior, 

 divergent horns which are not armed, but in G. porceUi they are 

 armed (fig. 15) with minute serrations on their inner margins and 

 teeth at their tips. Mjoberg observed that these horns were drawn 

 back and forth and outward by the action of muscles attached to 

 the posterior tendon. I have confirmed his observation by noting tho 

 action of the mouth parts in live specimens. 



It is very probable that G. porceUi used this cutting or piercing 

 hypopharyngeal apparatus by thrusting it into the mouth of a liair 

 follicle then drawing the horns sidewise and cutting or abrading the 

 skin. I have never observed this species resting with its body 



