26 
Transactions of the Society. 
list, and they have been rapidly increasing in number ever since his 
time. This book of Fiirstenberg’s contains a good example of how 
even industrious and careful men may be led away by their fancies. 
In every one of the really splendid illustrations the mites are clearly 
depicted as possessed of two pairs of chelate mandibles, a thing not 
really found in any one of them or in any other known Acarid. The 
different Itch-Mites have been described not only from man and all 
his ordinary domestic quadrupeds, but also from the dromedary, llama, 
wombat, fox, wolf, capybara, lion, hyaena, &c. Scraping hyaenas may 
not at first sight appear to be a pleasant occupation, but probably the 
investigations were conducted on dead specimens. 
Closely allied to the Itch-Mites are the harmless Bird- Parasites, 
the Analgesinae, familiar to all of you from the preparations of the late 
Mr. Cocken. It is a sub-family containing an immense number of 
species, which have been enormously added to by the researches of 
I)r. Trouessart among the bird-skins in the Paris and other museums. 
These creatures, particularly the males, often have very eccentric 
forms, but there is not amongst them perhaps anything stranger than 
Freyana heteropus, a parasite of the cormorant, which was originally 
made known in a paper read to this Society in 1881. Probably the 
male of this species and that of the equally curious Freyana caput - 
medusse , subsequently discovered by Trouessart on the gannet, are the 
only instances in the whole family of any departure from strict 
bilateral symmetry ; but in this Acarid the second leg on one side is 
very greatly enlarged, being much longer than its fellow on the 
opposite side ; not only is this so, but the enlarged leg is supported 
by a much stronger and quite differently arranged sternal skeleton 
from that of the other half of the body. Three years after my paper, 
Trouessart, who had accidentally missed it, published a description 
of the same species, supposing it to be new ; some time afterwards it 
was remarked that whereas in my drawing the left leg was the enlarged 
one, in Touessart’s it was the right ; and then arose the question 
which was in error ; it turned out that neither was ; my specimens 
had the left leg enlarged and the left side of the body with the 
strongly arranged skeleton ; Trouessart’s had the right leg enlarged 
and the right side with the interlocked skeleton, and it now appears 
that not only are these two forms about equally common, but also it 
sometimes happens that one leg of the first pair, or more rarely, the 
first and second leg on one side is enlarged, and the sternal skeleton 
varies accordingly. The office of the enlarged leg is to hold the female. 
The great group of the Tyroglyphidse or Cheese-Mites is by many 
authors included in the Sarcoptidse ; I cannot myself agree in this, 
they seem to be too different for such an arrangement ; but they are 
undoubtedly allied families. Although it has such a homely type as 
the common Cheese-Mite, this family includes many of the most 
beautiful forms in the whole of the Acarina. But perhaps the most 
striking point in connection with it is that it is here that the curious 
