110 
Guide to Arachnida. 
Table-case 
No. 25. 
Table-case 
No. 26. 
Sub-order II.— CRYPTOSTIGMATA. 
Acari with the tracheal spiracles situated in the articular 
sockets of the four pairs of locomotory appendages. The integu- 
ment is thickly and continuously chitinized, and shows no sign of 
segmentation. 
This sub-order contains the single family Oribatidae, sometimes 
known as beetle-mites, on account of their hard, black, shiny 
integument. They are not parasitic, but live in moss, under stones, 
etc., in damp places. 
An enlarged drawing of an Oribatid mite ( Notaspis bicolor) is 
on view in Table-case 25. 
Sub-order III.— METASTIGMATA. 
Acari with the tracheae opening by a pair of stigmata, situated . 
above and behind the base of the fourth or fifth or sixth pair of 
appendages. This sub-order contains two families : Gamasidae, 
Ixodidae. 
Fam. — Gamasidae. 
There is no serrated beak in 
these mites. 
They live for the most part a 
non-parasitic life in damp or moist 
localities, and prey upon organisms 
smaller than themselves. Many 
of them are found habitually upon 
large insects, like beetles, but 
apparently for the purpose of loco- 
motion, not of parasitism. Some 
members, however, are parasitic 
upon mammals and birds. 
Fam. — Ixodidae. 
Gamasus coleoptratorum (mag- „ 
nified). (After Berlese.) The coalesced basal segments ol 
the appendages of the second pair 
are produced in front into a cylindrical piercing process, or beak, 
furnished with recurved teeth. The appendages of the first pair 
are still pincer-like, but are much modified. 
The Ixodidae, or Ticks, live as temporary parasites upon 
mammalia, birds and reptiles, whose blood they suck by burying 
their mandibles and beak in the skin. The females quit their host 
