29 
The President's Address. By A. D. Michael. 
quite lately been confirmed by Moniez, who has been studying 
Tyroglyphus mycophagus , Megnin’s species, and has come to con- 
clusions absolutely identical with my own. There is a genus of 
Tyroglyphidse, called Glyciphagus, closely allied to Tyroglyphus, and 
it seemed strange that there should not be an Hypopus-stage here 
also ; but although Megnin, and I, and others hunted among the 
millions of Glyciphagi which are found in favourable situations, we 
could not find the Hypopus. About 1885 it struck me that amongst 
the immense numbers of cast and dried-up skins of Glyciphagus 
spinipes and G. domesticus which one finds in old barns, &c., certain 
of them looked different from the others, having a more opaque 
cuticle and more apparent contents. I transferred these to my 
breeding-cells and found that they were not dead at all, but that 
nearly adult nymphs emerged from them. I also observed that the 
case, as I called it, from which the nymph of G. spinipes emerged did 
not appear wholly empty ; I cut some open and found that each con- 
tained a cast skin resembling that of a Hypopus. I then dissected 
some of the cases at an earlier stage, and there I found a Hypopus in 
a somewhat imperfect state, alive and just able to crawl a little, but 
white and soft and unfit for exterior life. It seems, as far as I could 
trace it, that this Hypopus never emerged, but passed the whole stage 
inside the case, only the more adult nymph, which is formed within 
the Hypopus, emerging after the ecdysis. Thus the Hypopal stage 
appears to be dying out here, and in G. domesticus it seems to have 
become even more vestigial, for all that can be found is a proto- 
plasmic mass, the shape of a Hypopus it is true, but without legs or 
movement. Megnin, who found something still more rudimentary, 
where all shape of a Hypopus is lost, thought that these cases might 
be blown about by the wind and the species thus distributed. 
From the Tyroglyphidse to the Gamasidse is a great jump, for, in 
spite of the absence of eyes before mentioned, the latter is one of the 
most highly organized of Acarine families ; but time is short, and I 
have been a good deal interested in them of late. Some years ago 
Sir John Lubbock sent me a very curious Gamasid, which he had 
found in one of his ants’ nests, that of Lasius flavus. Haller had 
previously found an equally strange but quite different Gamasid in 
the nests of Formica nigra. I had long wished to pursue this subject 
a little further, and in the spring of 1891, when I was staying in 
Corsica, and in the Tyrol near Innsbruck, I made a systematic hunt 
of ants’ nests, with the result that I found no less than nine species 
of Gamasids, all except one new to science, living in the ants’ nests 
searched on friendly terms with the ants. Each species of Gamasid 
associated with one or two species of ant only; so that, after a 
little experience, I got to know what species of Gamasid I was 
likely to find when I saw what the sort of ant was. The ants 
seemed to take some care of the Gamasids, and would sometimes 
carry them oif to a place of safety when the nest was disturbed. 
It was extremely difficult to find out what office the Gamasids per- 
