( cli ) 



the single claw of Anoplura and some mammalian Mallophaga 

 corresponds to the outer ( = anterior) claw of other insects. 



The second organ by which Epizoa with sucking mouth- 

 parts fasten themselves to the host is the proboscis. A 

 permanent fixture is achieved by driving the proboscis deep 

 into the skin, as is done by ticks. This tick-like fixing is 

 found among the fleas in certain species, either in both sexes 

 or, as is usually the case, only in the female. The rabbit- 

 flea, and the species of Echidnophaga may be mentioned as 

 examples. The mandibles and upper lip of these fleas are 

 very strongly developed, the mandibles having densely and 

 deeply serrated edges, by means of which these fleas are 

 anchored. It is interesting to note that in some stationary 

 fleas which have large claws the proboscis is relatively small 

 (Malacopsylla) ; while in stationary fleas anchored by the 

 strongly developed mouth-parts the tarsal claws have be- 

 come reduced, being in some species so slender and weak as 

 to be of no use as a means of fixation (e. g. in the Jigger). 



It is also possible that some other portion of the mouth- 

 parts serves the purpose of fixing in other Epizoa. The 

 so-called mentum of the beaver-beetle, Platypsyllus castoris, 

 for instance, is divided into three lobes posteriorly projecting 

 towards the throat; and the gular plate of some Mallophaga 

 is similarly divided posteriorly into two or three projecting 

 lobes (Ancistrona, Pseudomenopon) ; (cf. text-figs. 20 and 21). 



Fig. 20. Underside of head of Pseudomenopon tridens N. (1838). 

 „ 21. ,, ,, „ Platypsyllus castoris Rits. (1869). 



The permanently fixed Epizoa are exposed to the danger 

 of being torn off or squashed by the host. There is generally 

 some special provision against this danger. Either the skin 

 of the parasite is so very tough that the scratching and biting 

 of the host can do no damage of serious consequence to the 



