British Oribatidte. By A. D. Michael. 235 



is asserted by Megnin to apply to the Tyroglyphi, Glyciphagi, 

 Carpoglyphi, Gamasinse, and Tromhididx : it would therefore 

 from analogy be likely to occur in the Orihatidee, although I am 

 not aware that it has been observed, and if so these may well have 

 heeB. femelles accouflees, or, as 1 should call them, nubile females. 



I was curious to see how the casting of the skin was so 

 managed as to leave the pile of the dorsal parts on the back, and 

 thought this a favourable species to observe. I did not find any 

 difficulty in doing so. The skin splits along the edge, commencing 

 at the rear as before described, until it reaches the rear of the ver- 

 tex ; then the split, instead of continuing round the edge of the 

 cephalothorax, goes across the back, and the creature backs out of 

 the fore and lower part of the old skin, keeping the dorsal, or rather 

 dorso-abdominal, portion still on its back. There does not appear 

 to me to be any disintegration of the creature in mere changes of 

 skin. Every larva or nymph which I have figured or mentioned I 

 have assui'ed myself of by breeding it to the perfect form. 



Organs of Special Sense. 



As before stated, Oribatidx have not any visible eyes that have 

 yet been discovered. I have before expressed an opinion that 

 others of the Acarina whose condition is similar have some sense 

 of sight, or are, at all events, sensitive to light, which most of them 

 dislike ; in order to utilize this dislike in tracing sight further if 

 possible, I placed a living Eremseus ohlongus, one of the most lively 

 of the Orihatidee, in a large glass cell, putting a piece of moss in 

 the middle. I then arranged the Microscope so that the sun fell on 

 the stage, but placed a dark screen to throw it into shadow. I then 

 placed the cell on the stage, and watched until the mite was on the 

 raised edge of the cell, where they generally hke to be. I then 

 suddenly removed the screen ; the mite did not wander vaguely 

 about, but came down from the edge, and crossed the bottom of the 

 cell in a straight hne for the moss, under which he got ; the same 

 experiment repeated once or twice had the same result. I leave 

 my hearers to decide whether this does not indicate some sense of 

 sight. 



"What are called the protecting hairs of the stigmata were once 

 supposed to be organs of vision ; this was evidently incorrect, and 

 is long since exploded. The high authority of Nicolet and others 

 is in favour of their being simply protecting hairs. Doubtless the 

 contrivances by which stigmata and spu'acles are protected are various, 

 but it is generally apparent that they are admirably suited to their 

 purpose. It is not, however, at all clear how these hairs can be of 

 any protection ; there is never more than one on each side ; they 

 cannot exclude dust, &c., because whatever the form of the hair, 

 only the fine part is near the stigmatic opening, and they are too 



