THE ACABINA OR MITES— BANKS'. 



55 



There are a few parasitic forms; the entire family Dermanvssida' is 

 parasitic on birds, bats, rodents, etc. Two yenera of the true Gamasidjv 



are parasitic — Iht'iiKx/dmasus 

 on moles, and IiaiUtetld in the 

 ears of various animals. A 

 great many occur among de- 

 cavino- fallen hnives. A num- 



FiG. 99.— Gamasus sp. 



Fig. 100.— Gamasus sp., ny.mph. 



her of species have been taken in ants' nests. Some of these live 

 attached to the ants and obtain food from them. One species is so 

 found on a Scolopt)idt'<i. The relationship of the 

 other forms to the ants is not clear in all cases. It 

 has been shown by Michael that some species of 

 Livlaps feed upon the dead ants. It is therefore 

 probable that most, if not all, of these myrme- 

 cophilous forms are scavengers, and their pres- 

 ence useful to the health of the colony. The ants 

 sometimes take care of the mites when the nest is 

 disturbed, and carry them to a place of shelter. 

 One species of Za^A^w, L. eqititans^ w^asfrequentl}" 

 ol)served to jump up on an ant and ride about for 

 a while, the ant taking no notice of its rider. It 

 appears that each species of mite prefers to live 

 with a certain species of ant, but several kinds 

 of mites have been found in the same nest. The 

 mites disappear" W'h en the ants desert the nest. 



The superfamily Gamasoidea is divisible into 

 several natural groups, the relative importance of which has been vari- 

 ousl}" estimated by dift'erent writers. I shall consider that there are 



101.— Gamasvs 

 i.arva. 



