42 Transactions of the Society. 



the reasons, viz. firstly, I have, as stated ahove, bred a nymph 

 of the ordinary class of appearance through the transformation 

 several times and seen it change into listriatus, and it would 

 be something utterly opposed to the whole natural history of 

 Orihatidfe that after the change from the soft, light-coloured, 

 nymphal stage, to the hard, apparently adult, stage, the seeming 

 adult should pass through a new transformation into a different 

 adult, lighter and softer than itself; it would be introducing a new 

 stage unknown among Orihatidse, and indeed unknown among 

 Acarina, and it would be quite exceptional for a nymph of one 

 of the Orihatidse to be harder and darker than the adult ; secondly, 

 in the genus Nothrus one would expect the nymph to resemble 

 the adult instead of being totally different from it, and a nymph 

 does exist which resembles palustris very closely (being light- 

 coloured, as might be expected). I am indebted to my friend, 

 Mr. George, for three or four living specimens of this nymph, 

 which I am sorry to say I did not succeed in breeding through, 

 but it looks the right size for palustris, which cannot be said of 

 histriatus, so that although I have not bred it, it seems very 

 probable that it is the real nymph of palustris, and moreover it is 

 figured by Koch as a separate species under the name of Nothrus 

 palliatus,* and Nicolet says in oue place (p. 389) that Koch's 

 ipalliatus is a nymph of palustris in a different stage ; while in 

 another place (p. 396) he says it is the nymph of N. sijlvestris. 

 I do not know of any instance among the Orihatidse where the 

 nymph at different ages varies at all to the extent of the wide 

 divergence between Koch's palliatus and Nicolet's histriatus. 



If, then, other zoologists should agree with me that these 

 facts show that histriatus is not a nymph, but an adult, what genus 

 does that adult belong to ? Clearly not to Nothrus, because it has 

 monodactyle claws, and I venture to think that it is one of the 

 Hermannia, although the back is not as arched as is usual in that 

 genus ; but if it be not one of the Hermannia then it does not 

 belong to any existing genus, and I cannot see any distinction of 

 sufficient importance to justify a new one, the form and position of 

 the epimera, the palpi, the labium, and maxillae, all of them important 

 and characteristic points, agree well with Hermannia, and so do the 

 general form of the cephalothorax, the position of the stigmata, and 

 the form of the stigmatic hairs, and these points seem to me to 

 outweigh the somewhat unusual form and marking of the abdomen. 



Before leaving the subject of these aquatic or semiaquatic 

 Orihatidse I may remark that, in most of them, the stigmata and 

 stigmatic hairs, especially the latter, are less developed than in the 

 terrestrial species; this doubtless is a modification useful in 

 consequence of the different medium in which the creature lives. 



* Loc. cit., Heft 30, pi. 4. 



