( cl ) 



also frequently the case in other insects. We have not noticed 

 any special sexual adaptation of the claws in Epizoa, but the 

 tarsi have often a different covering of bristles in the sexes. 



There is a single claw in some mammalian Mallophaga and 

 in the Anoplura (text-figs. 16 and 17). This claw is so 

 constructed that the insect can take a firm hold of a hair of 

 the host. It is singular that this kind of claw should be found 

 only in those two groups, which are usually placed far apart 

 in the system. If there is really no relationship between the 

 Anoplura and mammalian Mallophaga, the close agreement 

 in the claws is certainly most remarkable. 



All the other Epizoic insects have double claws of the 



Fig. 16. Tarsus of Pediculus humanus L. (1758). 

 ,, 17. ,, ,, Trichodectes caprae Gwilt (1843). 

 „ 18. ,, ,, Ancistrona vagelli Fabr. (1787). 

 ,, 19. ,, „ Adroctenes horvathi Jord. (1911). 



sickle-shaped type usually found in insects (text-figs. 18 

 and 19). In some groups (the majority of fleas) the claws 

 have a large basal tooth, in other cases they are quite simple, 

 many intergradations occurring. Asymmetrical claws are 

 found in some genera of Polyctenidae (text-fig. 19) and of 

 Cimicidae, the inner or posterior claw (i. e. posterior if the 

 leg is stretched out at right angles to the body) being smaller 

 than the outer one. In this point the three groups of Ecto- 

 parasites mentioned agree with the Rutelid beetles and the 

 $ $ of the Agaristid genus Chelonomorpha, while in the butter- 

 fly sub-family Acraeinae the opposite development has taken 

 place, the inner claw being the larger one. Among the 

 Pupipara also some slight asymmetry in the claws is found ; 

 here, as in the Cimicidae and Polyctenidae, the inner claw 

 being the shorter one. It appears, therefore, probable that 



