PARASITES FREE DURING THEIR WHOLE LIFE. 135 



on the small bat {Pipistrella) an acaride (Caris eUiptica) 

 and a new Ixodes w^hich we have described in a special 

 memoir on the parasites of the Cheiroptera, Mr. Lucas 

 caught an ixodes on a dog, and kept it alive long enough 

 distinctly to see it lay eggs which proceeded from an ovi- 

 duct. These eggs formed masses attached to the 

 abdomen of the mother. 



An acarus {Dermani/ssus avium) is found on birds, 

 and multiplies with such rapidity that it completely 

 exhausts those on which it has established itself. It 

 has been seen accidentally on man. An instance is 

 recorded of a woman w'ho could not get rid of these 

 parasites, because she passed every day through her hen- 

 house in order to get to her cellar, and the frightened 

 fowls threw down upon her a perfect shower of acaridse. 

 Not long ago mention was made at the Academy of 

 Medicine at Paris, of a sarcoptes {S, mutans), which 

 produces a disease among fowls, especially on the cock 

 and hen, and which passes from these to the horse and 

 other domestic animals. This sarcoptes prefers to live 

 under the epidermis of the feet. Eeptiles are not free 

 from its attacks, for it is often seen on lizards and 

 serpents. We have found a very curious one on the 

 skin of a gecko from the south of France. 



Many insects are always covered with certain species 

 of acaridae. Every entomologist knows that the body of 

 the " watchman " beetle always has some of these, like 

 little living pearls, which wander especially on the under 

 side of the abdomen. It is the same with a small cole- 

 opterous insect that is found abundantly wherever there 

 is any decomposing matter. Leon Dufour gave himself 

 up to the study of some of the parasites of insects, and 



