38 Transactions of the Societij. 



shape, as if cut with a knife ; thus in Scutovertex seulptus the 

 tlorso- abdominal portion spHts neatly off, and the creature emerges 

 through the opening, leaving the rest of the skin uninjured, 

 and looking like a manufactured article with a cover which 

 takes off. 



In the nymph of Tegeocranus latus the dorso-abdominal cast 

 skins lie flat on the back like a round buckler, forming a series of 

 concentric ellipses. In the nymph and adult of Nothrus thele- 

 proct'us the skin that is carried is what is usually called shield- 

 shaped, but instead of lying concentrically, the posterior ex- 

 tremities all start from almost the same point, so that the anterior 

 margins are far wider apart than the posterior, and they look as if 

 the top ones had slipped back ; the edge of each skin is a little 

 curled down so as to increase the apparent thickness. In the 

 nymphs of Oribata quadricornuta the skins are piled up in an 

 irregular lump on the back, while in the nymphs 6f Leiosoma 

 ])almicincta they also rise concentrically from the back, but in a 

 regular cone, like a series of limpets of diminishing size. In the 

 mature Bammus verticilipes the cast skins also assume a conical 

 form, but a far more elongated one, and, instead of standing 

 straight up, they are fixed on the hinder part of the abdomen, and 

 extend far beyond the posterior margin of the body, so that the 

 Dameeus, which really has a short, rounded abdomen, seems to have 

 a long pointed one. The strangest instance, however, that I have 

 seen is in the adult of Nothrus segnis; the abdornen of the 

 nymph of this species ends in two long, conical, tail-like projections ; 

 these are not found in the adult, but, as usual in the genus, there 

 is a great resemblance between the nymph and perfect form, and 

 these conical projections are replaced by bifid apophyses, which, 

 however, are concealed during the whole life of the creature, unless 

 some accident removes the cast skin, because, although the adult 

 does not retain the dorsal skin, yet it keeps the skin of the two 

 conical projections, each of which contains one of the apophyses as 

 in a bag, and to each cone of skin is attached a long, narrow 

 strip of the nymphal skin which makes a sort of light border along 

 the side and hind margin of the adult, and gives it a very curious 

 appearance : the apophyses can usually be well seen through the 

 cone of skin, particularly when rendered transparent by tur- 

 pentine, &c. This arrangement is shown at Plate V. Fig. 5. 



Aquatic or Amphihious Species. 



As far as I know, all previous writers have treated the 

 Orihatidse as a purely terrestrial family ; a year or two ago, how- 

 ever, when searching for rotifers in pond water which I had 

 obtained near Epping, I was struck by a mite, apparently at home 



