162 BRITISH TYROGLYPHIDjE. 



In 1892 Prof. R. Monier made a careful study of 

 the life-history, etc., of Tyroglyphus mycophagus 

 (Megnin's species *), with the result that he entirely 

 agreed with and confirmed my conclusions in the 

 matter which are stated above. 



There may fairly be said to be three distinct types 

 of Hypopus now known ; or perhaps it would be more 

 correct to say two which are certainly known to be 

 hypopial and one which is supposed to be so. The 

 two which are known to be hypopial may conveniently 

 be called " the ordinary Hypopus type " and " the 

 Homopus type :" the uncertain one can be designated 

 " the Trichodactylus (or Trichotarsus) type. 5 



The ordinary hypopial type has already been 

 roughly, but for the present purpose sufficiently 

 described on pages 144 and 148 ; but it must be under- 

 stood that the fourth pair of legs do not invariably end 

 in setaa without claws in all species, they may be 

 provided with claws ; and of course there are other 

 considerable differences between species ; but the 

 general character is the same. Hypopi of this type 

 are eminently fitted by nature to cling tightly by the 

 suckers on their ventral surface to smooth chitinous 

 insects and other polished surfaces, they are difficult to 

 detach, are not easily injured, and are proof against a 

 great amount of sun and drought; so that they are 

 almost ideal travelling forms to be carried about by 

 insects and larger chitinous Acari, etc. Illustrations 

 of this type of Hypopus will be found at PL II, figs. 

 6 10, Histiostoma rostro-s erratum, PL IV, fig. 3, H. 

 spinifer, and fig. 6, H. pulchrum, and on the plates of 

 Histiogaster corticalis, Tyroglyphus longior, T. myco- 

 phagus, and T. Wasmanni in Vol. II. 



Under favourable circumstances Hypopi of this 

 class often adhere to insects, or other creatures, in 

 astonishing numbers ; perhaps the most remarkable 

 instance of this is that recorded by Father Wasmann, 



* " Contribution a I'histoire natnrelle du Tyroglyphus mycophagus," 

 in ' Mem. Soc. Zool. France,' t. v (1892), pp. 584601. 



