288 
MR. A. D. MICHAEL ON THE LIFE-1ITSTORIES 
it appeared in 1778. In 1841 Gervais published a very short 
description and very imperfect drawing of a species which he 
called Glyciphagus cursor. In 1867 Eobin and Fumose pub- 
lished a very carefully prepared article in Eobin’ s ‘ Journal de 
l’Anatomie et de la Physiologie,’ in which, they, probably correctly, 
identified de Geer’s and Gervais’s species ; but, for some reason 
which is not quite apparent, they retained Gervais’s name, not 
de Geer’s. M. Megnin, in the observations mentioned below as 
having been made by him, has followed Eobin and Fumose in 
calling the species G. cursor : unfortunately neither of these able 
authors gives a figure of their G. cursor ; had Eobin and Fumose 
added such a drawing as they furnish of G. spinipes no doubt 
could arise as to what their species is. A good figure of what is 
apparently the male of G. domesticus is given by Berlese (Acari 
Ital. fasc. xiv. no. 3) ; it is accompanied by a short description, 
which, however, is supplemented by the notes to the same work 
(fasc. i. pp. 9, 10). This author, however, does not say whether 
he considers it to be identical with G. cursor , and the points 
which he gives for identifying his species do not admit of com- 
parison with those given by Eobin and Fumose for G. cursor. I 
imagine the two species to be identical. Under these circum- 
stances I have thought it best to give a figure of the female of 
the species I have been dealing with, to facilitate identification ; 
it is, I think, the G. domesticus of de Geer and Berlese, and, so 
far as I can judge at present, it is also the G. cursor of the other 
authors above named. 
It would be out of place here to give any formal description of 
such well-known creatures ; but as these two species, G. spinipes 
and G. domesticus, are commonly found together, and are not 
easily distinguished at first, although a little practice enables the 
student to do so with facility and certainty, it may be useful to 
state some of the principal characters by which they may be dis- 
tinguished ; these are : — Firstly, that the tarsi of G. spinipes are 
thickly clothed with very fine short hairs (PI. XVI. fig. 12), but do 
not bear any hairs much longer than the general average ; the tarsi 
of G. domesticus are smooth, but have a few straight hairs or 
spines much longer than those of G. spinipes (fig. 5). The hairs 
on the tarsi of G. spinipes are best seen in dry specimens using 
an amplification of from 150 to 200 diameters ; they are not so 
easily seen with lower powers nor in specimens mounted in bal- 
sam, or even in fluid. Secondly, the tarsi of G. domesticus are 
