P. A. Buxton 
149 
previous writers Lave done; this is more justifiable on physiological than on 
morphological grounds. The common itch mite of man stands as Sarcoptes 
scabiei de Geer, 1778, var. hominis (Hering, 1880); that of the horse as S. scabiei 
var. equi (Gerlach, 1857). 
2. “ Sarcoptes scabiei crustosae ” Fiirstenberg. 
Fiirstenberg differentiated a species under this name, giving as its character 
its shape, which is ‘‘rounded, slightly longer than broad,” and the greater 
length of one of the lateral setae, almost certainly the seta which I have 
lettered L 2. Canestrini and Kramer say “dorsal scales blunt; no bare area 
(Blosse). Spines long, acute, slightly bent. Anterior arm of epiandrium 
strongly developed and reaching the epimere. Male 170 x 150 microns, female 
410 x 340.” 
I have examined a series of specimens obtained by Dr Wallace Beatty from 
a case of Norwegian crusted scabies, and kindly lent to me by Col. A. Alcock, 
F.R.S., I.M.S. There is no doubt that these specimens came from genuine 
cases of Scabies Norvegica. Beatty has figured two cases (1913, 1915) and I 
have examined mites from each of these. I find that adults may be separated 
from those of typical S. scabiei var. hominis on one character only, and that 
is the greater size of the spines (Figs. 3 and 4). One must always exclude the 
fourth spine of the outer row from one’s measurements because of its peculiar 
shape and proportions: the other spines measure 34 microns or more, and are 
also slightly thicker than those of S. scabiei var. hominis. The second spine of 
the inner row measures 42 and 45 microns in two females examined, the second 
in the outer row 36 and 42 microns. I can find no other points of difference 
whatever. The specimens at my disposal have been dried, and it is therefore 
impossible to measure length and breadth, but their size and proportion do 
not appear to differ from those of typical S. scabiei. As the only characters 
by which this mite may be distinguished require an oil-immersion lens and 
a micrometer for their proper appreciation it appears best to relegate it to 
varietal rank. It is unfortunate that this form was originally named Sarcoptes 
scabiei crustosae. The third name was not used in a varietal or subspecific sense, 
and there is no doubt that “ scabiei crustosae ” was regarded as a specific name. 
It is technically invalid, because it does not conform to the binomial principle. 
Later writers have regularized matters by writing scabiei-crustosae with a 
hyphen, as an emendation. The name of this variety is therefore Sarcoptes 
scabiei var. scabiei-crustosae (Fiirst.). 
3. Norwegian crusted scabies. 
Dr Wallace Beatty’s specimens are interesting in another way: the pre¬ 
parations, which are made in Farrant’s medium, are full of a species of Asper¬ 
gillus. That the mould is not a contamination is proved by the fact that the 
conidiophores of the mould are to be found in all parts of the preparation. If 
