294 Sarcoptic Scabies 
but deteriorate in flesh and in egg-laying. Cocks suffer most, and sometimes 
die in a cachectic state. The disease is most prevalent in spring and summer. 
The varieties of laevis which have been founded by various writers are: 
Fossor Ehlers, 1873, on the passerine bird Munia maja, and glaberrimus 
and philomelae described by Sicher, 1893, from Dendrocopus medius and 
Luscinia philomela respectively. 
Railliet’s type species is sometimes known as C. laevis var. gallinae. Ehlers 
(1873, “Die Kratzmilben der Vogel, 1 ’ Zeitschr. /. wiss. Zool. , pp. 228-253, 
Pis. XII and XIII) gives beautiful figures of fossor (under the genus Derma- 
toryctes). Its chief characteristic is the possession of four claws on the female 
tarsus. The epimeres of legs 1 are free. 
Sicher (1893, pp. 134 et seq.) describes glaberrimus and philomelae: 
Glaberrimus has the epimeres of legs 1 free, and no posterior hairs; in 
philomelae the epimeres of legs 1 meet at an obtuse angle, and there are six 
hairs of about equal length at the posterior end of the body. 
The males are not known. 
CONCLUSIONS. 
We have little doubt that future investigators will regard Sarcoptes, 
Notoedres and Cnemidocoptes as generically distinct. Cnemidocoptes, always 
parasitic on birds, and comprising members of different habits—scab forming 
or depluming—would seem to form a compact group for a separate research. 
Notoedres , attacking small mammals, but often communicated by them to 
the larger mammalia and to man, cannot well be dissociated from Sarcoptes 
in any study of the acarine causes of scabies, but the foregoing resume of our 
present knowledge of the subject makes it abundantly clear that the urgent 
and immediate need is to clear up the confusion which exists with regard to 
the last-named genus. Whether different forms are to be regarded as species, 
varieties or races is, after all, a minor matter, and one as to which differences 
of opinion may well continue to exist after the most thorough investigation. 
What is important is that one form should be so completely studied that 
differences of structure in forms thought to be distinct from it may be clearly 
recognised, and when this has once been accomplished a foundation will at 
least have been laid for a comparison between the Sarcoptes of the different 
animals. The human Sarcoptes would probably be selected for this purpose. 
If so, care should be taken that the patients who supply the material should 
not be men occupied in the tending of domestic animals, and especially of 
horses, lest there be any suspicion of contagion from such sources. There 
would be some advantages in selecting instead the form known as equi , which 
is easily obtainable, and in which the salient characteristics would seem to be 
more strongly marked. 
Any structural peculiarity which has been noted in any so-called species 
or variety should be specially looked for in the type selected for exhaustive 
study, Megnin’s experience being always borne in mind. He made a new 
