XVIII HETEROSTIGMATA—NOTOSTIGMATA 473 
(iv.) The CHEYLETINAE are remarkable Mites with fleshy, semi- 
transparent body, and enormously developed raptorial pedipalpi, 
which are extremely formidable weapons of attack. They do 
not creep or run lke most Mites but proceed by a series of short 
leaps. Cheyletus is the principal genus. 
The curious genus Syringophilus, which is parasitic in the 
interior of birds’ feathers, appears to be a degenerate Cheyletine. 
(v.) The ERYTHRAEINAE are minute, active Mites, usually red 
in colour, free-living and predaceous. 
(vi.) The TROMBIDIINAE include most of the moderate-sized, 
velvety red Mites which are commonly known as “ Harvest-mites,” 
and their larvae, the so-called Harvest-bugs, frequently attack 
man. Zvrombidium holosericeum is a well-known example. 
Sub-Order 6. Notostigmata.’ 
This sub-order has been established for the reception of the 
curious genus Opilioacarus. 
Fam. Opilioacaridae.— Mites with segmented abdomen, leg- 
like palps, chelate chelicerae, and two pairs of eyes. There 
are four dorsal abdominal stigmata. Four .species of the sole 
genus Opilioacarus have been recorded, O. segmentatus from 
Algeria, O. italicus from Italy, O. arabiews from Arabia, and 
O. platensis” from South America. 
1 With, Vid. Medd. 1904, p. 187. 2 Silvestri, Redia, ii., 1904, fase. 2, p. 257. 
