288 ARACHNOIDEA, 



CASE left in the body. They seem pretty generally distributed. They 

 are found in the dust of hay, fodder, and straw, in old chaff, old 

 grain, old meal, old flour and old linseed meal. M. Fumouze met 

 them occasionally in different parcels of Cantharides collected in 

 France. They were very rare in foreign parcels. Prof. Robin 

 mentions that several times specimens have been sent to him, 

 which had been found on the surface of the human body, or in 

 stools, &c., without their having caused any accident. He suggests 

 that they doubtless came from some of the preceding objects, or 

 from the linseed flour used in cataplasms. They are also met with 

 in the feathers and hair of animals preserved in collections, and 

 in insects that have been attacked by Glyciphagi or Tyroglyphi. 

 Mr. Brady also figures a specimen of this species, which he found 

 in his dredgings, and described as C. robertsoni, which had no 

 doubt been blown into them or otherwise introduced from with- 

 out. We thus see that although in itself solitary, it is met with 

 in all sorts of places, more especially in those where other gre- 

 garious Acari most do congregate. But we should no more think 

 that it was there for the purpose of feeding on these vegetable 

 stuffs in which it is found, than we should admit that a cat eats 

 hay, because it was found in the midst of a rat infested-haystack. 



Mr. Beck, by keeping this species in confinement, was enabled 

 to ascertain the remarkable fact that the phenomena of Partheno- 

 genesis occur among Acarids as well as in other orders of insects. 

 He began by finding that some broods of other Acarids which he 

 kept in confinement were mysteriously disappearing, and at last 

 traced the mischief to one individual of this species. It proved 

 to be a female, which laid eggs, and from them he reared 

 numerous individuals, which, however, all proved females. Find- 

 ing that they laid eggs he suspected Parthenogenesis, and tested 

 the fact by isolating a single individual in a glass cage immediately 

 after it had been hatched. It laid eggs, and it ended by his 

 rearing three successive generations from it without any interven- 

 tion of the male. The female of this species is very careful of her 



