140 
not vouch that I have not overlooked any important 
fissure or a little group of fissures, as is often con- 
nected with the greatest difficulty to examine carefully 
from all sides under the microscope all the different 
joints of a leg; and a small rotation of a joint is suffi- 
cient to render it impossible to see all fissures, as the 
portion towards the edges cannot be seen distinctly. 
My searching for the sense-organs led me to the 
discovery of the remarkable supplementary spi- 
racles on the tibiæ in Phalangioidæ. I have 
almost entirely omitted the great order of the Acarv, 
being in want of material of and sufficient knowledge 
to the numerous and most different families; I have 
not seen any specimen of Palpigradi (Koenenia) *) 
and also entirely omitted Linguatulida and Tardi- 
grada. : 
The succession in which the 8 orders are mentioned 
is chosen of practical regards. I have quoted a number 
of works, essentially or exclusively systematical, but as 
few as possible not to get into prolixity. I mention a 
smaller number of anatomical papers, partly those which 
have been omitted by Gaubert or have been published 
later, partly a few that required a direct reference. 
Readers wanting a more additional information f. ex. 
about the history of the sense-organs are referred to 
the work of Gaubert. Of practical reasons I mention 
the papers that are quoted by one order, as a rule, in 
the beginning of its treatment, while the few works 
*) In June this year I have taken a series of this extremely 
interesting form in forests in Calabrien, in the neighbourhood 
of Palmi and Scilla), but the plates belonging to this paper 
was then engraved, and the study must be postponed to a 
subsequent occasion, © 
