[332] 



ON THE OCCURRENCE IN CANADA 



OF 



TWO SPECIES OF PARASITIC MITES. 



BY J. B. TYRRELL, B.A., P. G. 



Sarcoptes minor, var. Cati, Hiring. 



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 eellular 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, Hering ; S. notoedres, Bourguinon and Delafond). It is 

 the smallest speeies 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 ill many plaees 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 sniallei-. 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 S. scabiei, covered with a thin transparent 

 epidermis raised into minute folds, which follow more or less closely 



