XVIII ANATOMY 459 
living Mites which have undergone no great modification of the 
mouth parts two other portions can be distinguished, the upper 
hp or “ epipharynx,” and the “ lingua,” which forms the floor of the 
mouth, and is for the most part concealed by the maxillary plate. 
The legs are usually six- or seven-jointed, and are subject to 
great variation, especially as regards the tarsus or terminal joint. 
This may bear claws (1-5) or sucking disks, or a combination of 
the two, or may simply take the form of a long bristle or hair. 
The Cheese-mite has a claw surrounded by a sucker—like 
Captain Cuttle’s hook within his sleeve. The claws of those 
species which are parasitic on the hairs of animals are sometimes 
most remarkably modified. 
Internal Structure—The minute size of most Mites has 
rendered research upon their internal structure a matter of great 
difficulty, and there are still many obscurities to be removed. 
Those forms which have been sub- 
. Jected to examination present a 
tolerable uniformity in the structure 
of the principal organs, but the brief 
description here given will not, of 
course, apply to aberrant groups 
like the Vermiformia. A marked 
concentration 1s noticeable through- 
out the Order, and is best exempli- 
fied by the nervous system. 
The mouth leads into a sucking 
pharynx, which narrows to form the 
oesophagus. This passes through 
iieheiomve amass in the usual el areatiy enlarged: 
Arachnid fashion, and widens to C, C, Lateral caeca of stomach ; g, 
form the ventriculus or stomach. ae ine ef ee ied 
The oesophagus varies considerably cular gland; ps, pseudo-stigmatic 
: ote : : d organ ; sf, stomach ; ?¢7,tr, tracheae. 
in width in the various groups, (Partly after Michael.) 
being very narrow in those Mites 
which merely suck blood,-but wider in vegetable-feeders like 
the Oribatidae. 
The stomach is always provided with caeca, but these are not 
nearly so numerous as in some other Orders of Arachnida. 
‘There are always two large caeca directed backwards, and there 
may be others. They are most numerous in the Gamasidae (see 
oe 
