[332] 
ON THE OCCURRENCE IN CANADA 
Or 
TWO SPECIES OF PARASITIC MITES. 
BY J. B. TYRRELL, B.A., F.G.S. 
SARCOPTES MINOR, VAR. Cati, Hering. 
A short time since my attention was called to a cat whose face had 
apparently been scratched and torn and was now covered by a moist 
scab, which was especially noticeable at the base of the nose and 
around the eyes ; however, on turning back the hair from the top of 
the head and base of the ears the same diseased condition was seen 
to prevail, though not to such a marked extent. 
On removing the scab, the skin was found to be completely honey- 
combed, presenting the appearance of coarse cellular tissue, in the 
cells of which, and among the roots of the hair which had been 
pulled out with the scab, could be seen a number of exceedingly 
small white specks which, when picked up on the point of a needle, 
and placed under the microscope, proved to be a small itch-mite 
belonging to the species described by Fiirstenberg as Sarcoptes minor 
(S. cati, Héring ; 8. notoédres, Bourguinon and Delafond). It is 
the smallest species as yet described, not being more than half as 
long as Sarcoptes scabiei, the common itch-mite which infests man. 
As this minute parasite has in many places proved very fatal to 
our domestic favourites, it will be interesting to notice shortly the 
peculiarities of its structure, and then to look for a moment at the 
way in which it commits its depredations. 
The general shape of the body is almost globular, being slightly 
longer than broad, the female being about .12 mm. long and .1 mm. 
broad, the male somewhat smaller. To the naked eye it appears as 
a shining white spot, but under the microscope it has a grayish white 
appearance with light brown colored markings, showing the position 
of the chitinous skeleton. 
The body is, as in 8. seabiei, covered with a thin transparent 
epidermis raised into minute folds, which follow more or less closely 
