1910 ENTOMOLOGICAL SOCIETY. 97 



Family Hydrachnidae. 



Many species belonging to this family have been obtained by means of the 

 aquatic mite trap, but so far only two species have been identified. They are 

 closely related to the Trombidiida>, but are distinguished from them by means of 

 their flattened and hairy legs and other adaptations for their aquatic existence. 

 The young of this family are usually parasitic on water bugs and beetles, but the 

 adults, as a rule, live free in the water. 



Hydrachna helostomae, Eie. Attached to ventral surface of electric light bug. 

 T. D. J., Guelph. 



Hydrachna sp. Gills of Fresh Water Mussel. T. D. J., Guelph. 



Family Ixodid^. 



Five species of this family have been found in Ontario. They are the largest 

 of the mites and most familiar to ordinary people. The body is covered by a 

 tough leathery skin, which in the female when filled with eggs is shown to be quite 

 elastic by its great distension. They are usuallv known as ticks and are frequently 

 parasitic upon birds, reptiles, turtles and mammals. Their chief importance is 

 that they are transmitters of disease of man and domestic animals. 



Ixodes Marxi, Banks. On Eed Squirrel. T. D. J., Guelph. 



Ixodes Coolci, Pack. On Groundhog. T. D. J., Guelph. 



Boophilus hovis, Eiley. On imported cattle. T. D. J., Guelph. 



Dermacentor variabilis. Say. Dog tick. T. D. J., Guelph. 



Dermacentor alhipictus, Pack. Taken from moose. T. D. J., Northern Ont. 



Family Gamasoid^. 



Over thirty species are included m the Ontario fauna. Their habitat is of 

 the most varied character of all the Acarids, some parasitic, some predaceous, some 

 vegetarians, and some scavengers. The anatomy of this family is also very much 

 varied. Some have a hard cariaceous integument, others again are quite soft 

 bodied. Their legs are short and usually flat and broad. 



Gamasus attenuipes, Banks. Feedmg on turnip in Ontario Agricultural Col- 

 lege root cellar. T. D. J., Guelph. 



Gamasus posticatus, Banks. Under decaying maple leaves in College wood 

 lot. T. D. J., Guelph. 



Gamasus sp. Abundant in Ontario Agricultural College herbarium on pressed 

 specimens of Pear-leaf Blister-mite. T. D. J., Guelph. 



Gamasus sp. On decaying squash in Ontario Agricultural College garden. 

 T. D. J., Guelph. 



Gamasus sp. Under decaying tree in Ontario Agricultural College wood lot. 

 T. D. J., Guelph. 



Gamasus sp. Abundant on fruiting bodies of Brown Eot of Cherry (Sclero- 

 tinia fructigena). T. D. J., Grimsby, Ont. 



Gamasus sp. Under decaying hard maple leaves in Ontario Agricultural 

 College .wood lot. T. D. J., Guelph. 



Gamasus sp. In gall of Eriophyes on Aspen. T. D. J., Guelph. 



Gamasus sp. In horse manure at Ontario Agricultural College. T. D. J., 

 Guelph. 



5 E. s. 



