"..18 the president's address. 



cellcnt opportunity of using its long agile mandibles for capturing 

 its prey when the beetle is grubbing in the earth or dirt where they 

 abound. Slightly similar instances occur in other orders of beings, 

 thus the young Anodont, a bivalve mollusc, attaches itself to its 

 parent, or else to some fish, by a very long cable, which proceeds 

 from the foot ; and which persists through life after its use is over 

 in some mussels and pinnae, and is known as byssus. In the 

 gills of these Anodonts live the larvae of some species of Hydrach- 

 nidce, many of which are parasitic in the larval, but not in the 

 adult state. Parasitism is common among other members of the 

 Gamasidce besides Uropoda, but its nature varies considerably ; in 

 some cases the adult male, which is the most powerful and best 

 developed creature, is not parasitic, although the females and 

 young may be so ; and it is still a doubtful question whether these 

 seek only conveyance from their host or actually feed upon his 

 substance. Many arguments favour the latter view, but it is 

 difficult to see how a whole swarm of Gamasids manage to find 

 sufficient nourishment on the hard chitinous coat of such an 

 animal as the common dung-beetle, Geotrupes stercorarius. Some 

 Gamasids certainly seem to be true parasites ; thus many of those 

 found on bees die if removed from the bee, while others do 

 not. Two Gamasids which are unquestionably parasites, living 

 all their lives upon the same host, and feeding upon him, are 

 Dermanyssus avium, abundant in our poultry yards, and the 

 PterojHus of the bat, which latter is supposed to differ from all 

 other Acarina in having an octopod larva ; an allegation which it 

 seems to me must be received with caution. It shows how little 

 the Acarina are understood even by first-rate naturalists ; that 

 Van Beneden apparently supposes that Pteroptus does not belong 

 to the order. Another quaint acarine parasite of the bat is the 

 Otonyssus, a difficult creature to classify, which is generally found 

 on the ears of the bat, most often three or four clinging to the 

 extreme edge of the ear, and probably not any elsewhere. It seems 

 odd that the numerous parasites of bats should be so very special. 

 Neither Pteroptus, Otonyssus, nor the extraordinary Nycteribia 

 have any very close allies elsewhere. Another curious acarine 

 parasite of the bat, however, is in a different position — the Myobia 

 chiropteralis — which was first described in a paper read at this 

 Society, although a well-marked species, is closely allied to the 



