ON DEMODEX PHYLLOIDES. OT 
Demodex may be conveyed from dog to dog, yet experimental 
attempts to prove this have failed, and very often one dog in a 
kennel may be affected, and, although mingling freely with the 
others, may be powerless to infect these. 
2.—SYSTEMATIC POosITION. 
After discussing the results of previous observers as to the 
anatomy of Demodex, he concludes under his second heading that 
five well marked varieties may be distinguished, all referable to that 
genus, viz. : 
D. folliculorum hominis. 
D. folliculorum canis. 
D. folliculorum cati. 
D. phyllostomatis (Leydig). 
D. phylloides (Csokor). 
The genus he regards with Koch as forming an independent 
Family of the Acarina the Dermatophili. 
3.—NatTuRAL History or D. PHYLLOIDES. 
The form of the body and its division into three regions, head, 
thorax and abdomen (the last distinguished by the absence of 
appendages and of the chitindus framework present in the thorax), 
may be studied in Figs. 7 and 8. 
The result of a series of comparative measurements shows : 
1. That D. phylloides (length, male 0.22 mm., female 0.24—0.26 mm.) 
reaches the minimum length of D. canis, but never that of D. 
hominis. 
2. Head and thorax are together equal in length to the abdomen, 
while in D. canis they only form a third of the whole length of 
the body, and in D. hominis only a fourth. 
3. D. phylloides is comparatively almost twice as broad as D. canis 
or hominis. 
4. The head in D. phylloides is absolutely both longer and broader 
than that of either D. canis or hominis, a cireumstance which 
renders the analysis of the appendages of the head easier in this 
species. 
5. The egg is more oval than spindle-shaped, and both it and the 
larval stages are longer and broader than the similar stages in 
D. canis and hominis. 
6. There is more difference between D.-phylloides on the one hand, 
and D. canis and hominis on the other, than there is between 
these two last-mentioaed varieties. 
