THE PRESIDENTS ADDRESS. 215 



The ordinary Ixodes j'inaceus, called the dog-tic, seems to me to 

 bear somewhat the same relation to the harvest-bug that Demodex 

 does to Sarcoptes. If entitled to be called a parasite at all it is a 

 very temporary one. It lives in the ferns and bushes apparently 

 on vegetable food, but will undoubtedly attach itself to any passing 

 animal. Many authors consider that this creature produces irrita- 

 tion, so I suppose it must with some. Personally, I have often 

 found it on my arms after a day in the woods, but have not ever 

 found it out except by sight. It drives its rostrum, with the two 

 rows of great recurved hooks, right into the skin, and it is sur- 

 prising that the wound should not be more felt. Authors say that 

 if a drop of turpentine be placed on the Ixodes it will withdraw its 

 rostrum, and I suppose it must be so ; but those that have favoured 

 me with their attentions have not been kind enough to do this, and 

 I some time since received from Miss Ormerod a piece of ox-hide 

 which had come from South Africa in spirit. It had three very 

 large Ixodidce, close together, so firmly fixed in it that I had to cut 

 deeply into the hide with a dissecting-knife in order so release the 

 rostra. The bite of all the British Ixodidce is not painless, if I may 

 trust the assurance of a well-known entomologist, who told me 

 that on one occasion when he put his hand into a swallow's nest to 

 search for beetles the Ixodes inside bit like a dog. The severity of 

 the bite of the allied Argasidce is well known. 



You will find numerous other Acari treated as parasites of man 

 by various writers ; as to most of which it need only be said that 

 many Acari which are not parasitic are very small and very quick, 

 and very apt to get into unexpected places. 



One of the most curious forms of limited parasitism found 

 amongst Acarina is that of the Hypopus. In the collection of this 

 Society will be found a slide of a large flea with numerous Hypopi, 

 which were supposed to be inside it. A careful examination will 

 show that this is an error, and that the Hypopi are only between 

 two segments of the abdomen, being in the part where the anterior 

 edge of a segment is drawn within the posterior edge of the pre- 

 vious segment in a telescopic manner, thus providing a place of 

 shelter for the A cams. The Hypopus is usually a minute creature, 

 flat on thev entral surface, but entirely covered by a smooth, arched, 

 dorsal., chitinous carapace ; its hind legs end in hairs like those of 

 the itch-mites, and its mouth is rudimentary, consisting only of a 

 short, closed, membranous tube ending in two bristles. It is 



Journ. Q. M. C, Series II, No. 21. 17 



