164 BRITISH TYROGLYPHIDjE. 



clean themselves, and become coated with a dirty crust 

 which on the head, palpi, and limbs is especially repug- 

 nant to them. The immense numbers of Hypopi 

 clinging to the front legs prevent the ants from using 

 the comb, which these organs are provided with, to 

 clean the body. The mouth and its organs become so 

 covered with Hypopi that the ant can scarcely take 

 food. The Hypopi clinging to the antennae and palpi 

 render these important organs useless ; is it wonder- 

 ful, Wasmann asks, that the ant should fall into a 

 lethargy and die ? 



Wasmann also found great numbers of the Hypopi 

 of Histiostoma rostro-serratum in his ants' nests ; the 

 ant sometimes is covered with them ; as many as 150 

 to 200 would sit in a heap upon the head of one ant 

 and all the actions of life were arrested or interfered 

 with ; this species is not however confined to ants' 

 nests as T. Wasmanni is ; it swarms in enormous 

 numbers in most places where there is vegetable 

 matter in the early stages of decay, and the Hypopi 

 cling to passing creatures ; the ants searching for food, 

 etc., would doubtless bring them in in large quantities, 

 and the oftener and longer they searched the more 

 Hypopi would adhere to them ; they would attach 

 themselves to other suitable insects, etc., equally readily, 

 but the ants are there and do not fly and are in every 

 way convenient to ride upon. 



Wasmann found that the Hypopi of T. Wasmanni 

 were in greatest numbers on the head, abdomen, and 

 legs ; comparatively few being on the thorax ; and 

 that they almost always arranged themselves in the 

 direction of the long axis of the joint or segment they 

 were upon ; their anterior ends being directed toward 

 the point of the joint, or segment. The Hypopi of 

 H. rostro-serratum however did not exhibit any such 

 regularity of position but were in crowded masses, 

 principally upon the head. 



Wasmann' s observations are not the only ones which 

 tend to show that Acari which attach themselves to 



