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This order contains a very large number of species and has been 
arranged by Murray, a very recent English authority, into the follow¬ 
ing families and sub-families: 
Subdivisions of Acarina. 
Fam. 1. Trombidiidce. 
Sub-fam. 1. 
2 . 
Tetranychince , Spinning mites. 
Trombidiinm , Harvest mites. 
2. JBdelUdce , Snouted harvest mites. 
3. ffyclrachnidce, Water mites. 
4. G-amasidce, Insect mite-parasites. 
5. Ixodidoe, Ticks. 
6. Halacariclce , Marine mites. 
7. Oribatidce , Beetle-mites. 
8. Acaridoe. 
Sub-fam. 
1 . 
2 . 
3. 
4. 
5. 
Hypoderinaef Sabcutaneous mites. 
Hypopinae , Ichneumon mites. 
Tyroglyphinae, Cheese mites. 
Sarcoptinae , Itch and louse mites. 
j Phytoptinae, Gall and bud mites. 
The scab mite of the sheep, which is now believed to be the same 
species as that infesting the horse and ox, belongs to the eighth 
family, Acaridoe , and fourth sub-family, Sarcoptinae , which also con¬ 
tains the human itch mite, or mite that produces the disease in man 
known as the itch. 
The scab, as all are aware, is a skin disease analogous to the mange 
in the horse and itch in man, and, like these, is produced by a very 
small mite. It was for a very long time supposed that this mite was 
produced spontaneously, by an unhealthy and unclean condition of the 
flocks* or from insufficient or improper food, etc., and not from a 
preceding parent. According to Westwood, two such able entomolo¬ 
gists as Burmeister and Kollar leaned to the idea of equivocal gener¬ 
ation of these parasites. But such erroneous ideas as these in refer¬ 
ence to these mites have at last been corrected—at least so far as 
authors and naturalists are concerned—as it is now known that they 
are produced from eggs, deposited by parents similar to themselves. 
As before stated, the species belonging to the class Arachnida , are 
distinguished from insects and most other minute animals, by the 
fact that they possess four pairs of legs; though there are some ex¬ 
ceptions to this rule among the mites, some of which, in the perfect 
or full grown state, and several in the immature state, having only 
three pairs. 
The sub-family Sarcoptinae is distinguished from the other groups 
of the family by the striated or finely grooved skin; by the suckers 
with which the feet are usually provided; and by being destitute of 
eyes. 
* r have changed the termination of the sub-families to correspond with present custom 
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