No. 2. — On the Presence of Demodex folliculorum in the Skin of the 
Ox. By WALTER Faxon. 
Last January my attention was called to the diseased condition of 
cowhides received from Illinois and Minnesota by Webster & Co., of High 
Street, Boston. In the parts about the neck and shoulders, especially, 
the skins presented numerous slight swellings, which under pressure 
emitted a quantity of soft whitish matter. After being tanned and split, 
the leather appeared „disfigured with pits from one to six millimetres in 
width, which in many cases penetrated nearly through the thickness of 
the leather (Fig. 1). Some of these cavities were filled with a yellowish 
stuff easily removed by the point of a knife. In many of the samples 
eight or ten pits occurred within the area of one square inch, On placing 
a drop of the matter taken from the pimples of the hides under the mi- 
croscope, it proved to be a fatty substance containing multitudes of Demo- 
dex folliculorum. Sections of the skin showed the cavities to be diseased 
and enlarged hair-follicles (Figs. 2, 3, 4). All the infested pieces which 
I was able to obtain had been subjected to the lime-soak and other pro- 
cesses prior to tanning. I was therefore unable to make out the structure 
of the parasite as minutely as 1 might, had I fresh specimens at my 
command. 
Description. The body (Fig. 6) is of a long oval, flattened form, nar- 
rowing abruptly at the anterior end, but tapering gradually to the pos- 
terior extremity, which is blunt. There is no very marked division 
between the cephalo-thorax and the abdomen. Under a high magnifying 
power the abdomen is seen to be lightly annulated, the annulations being 
strongest toward the hind end of the body. 
On each side of the mouth is a large two- or three-jointed palpus, of 
which the proximal segment makes the bulk. The distal segment, bears 
two or three minute hooks. Toward the distal end of the proximal seg- 
ment of each palpus is a minute oval body. This is probably the struc- 
ture called an eye by Erasmus Wilson.* I take it to be a thickening of 
the integument, probably for the attachment of muscles, At the base 
of the palpi are some exceedingly minute structures (Fig. 7), the na- 
ture of which I could not determine. Above and within the palpi lie 
the mandibles, two styliform organs which rarely project beyond the 
median plate (epistoma), which seems to lie above all the other mouth- 
* Phil. Trans., 1844, Pt. I: p. 309. 
