46 THE PARASITES OF MAN. 
described in as few and simple words as possible, and as the 
portraits of all species found thus far in Minnesota will-be 
given, thoseinterested will find no troublein recognizing them. 
We divide the animal parasites mentioned in this report 
into two groups: 
1. EXTERNAL PARASITES (&pizoa) which live upon 
the skin, and 
2. INTERNAL PARASITES (Entozoa) which live in- 
side of the organs and tissues of their hosts. 
I. EXTERNAL PARASITES. (£pizoa). 
FACE-MITES; BLACK-HEADS. (Demodecide). 
ITCH-MITES. (Sarcoptide). 
HARVEST-BUGS; JIGGERS. (Zrombidiide.) 
GAMASIDS. (Gamaside. ) 
TicKs. (/xodide). 
SUCKING-LICE. (Fediculz). 
BITING-LICE; FEATHER-LICE. (J/allophaga). 
FLEAS. ( Siphonaptera) : 
LOUSE-FLIES. (//ippoboscide). 
OTHER FLIES. (/iptera). 
Bucs. (Hemiptera.) 
OTHER INSECTS. 
CAC Oe a eo Ow 
II. INTERNAL PARASITES. (Entozoa). 
FIVE-MouTHS. (Linguatulide). 
BOT-FLIES. ((Zstride). 
el 
I. EXTERNAL PARASITES (Epizoa). 
A. FACE-MITES: BLACK-HEADS. 
(Demodecide). 
These singular parasitic beings do not exactly fitinto any 
classification, at least naturalists have disagreed about their — 
true position until quite recently. But they are no doubt 
mites with quite an anomalous structure, so much so in fact 
that they might be said to form a sort of transition from 
annelids or worms to arachnids or spider-like animals. As 
they have many points in common with itch-mites, which 
