34 Transactions of the Society. 



Claparede has traced, with his accustomed care and minuteness, 

 the whole development of H&plojjhora dasypus, or as he calls it 

 JEZ". contractiUs. Tliis is one of the eleven species Nicolet traced ; 

 he calls it H. nitens. 



Although these two are the only writers who have treated of 

 the nymphs as nymphs, they are not the only ones who have 

 noticed the creatures ; C. L. Koch,* in his work on the Acarina, 

 &c., has figured and described many of them, but he has supposed 

 them all to be adults of separate species, and even made them the 

 types of new genera, which error he has confirmed in his subsequent 

 work.t 



Nicolet pointed out Koch's error in many instances, and also 

 expressed his opinion that the whole of Koch's genera, Murcia, 

 Celseno, Hyjwchthonius, &c., consisted of nymphs ; I believe Nicolet 

 is correct in this, but, of course, he could only assign Koch's so- 

 called species to their respective adult forms in those instances 

 where he himself had traced the life-histories. It will be seen by 

 the latter part of this paper that among the species whose histories 

 I have traced, as I believe for the first time, are six nymphs which 

 had been figured and named by Koch as distinct species. 



I have pointed out in my former paper that it is very difficult 

 to avoid falling into Koch's mistake, and that it was very natural 

 that he should have made it ; in confirmation of this, and to show 

 how necessary it is that the life-histories should be known, I may 

 mention that one or two present writers appear to be doing the 

 same thing. 



The life-history, for the purposes of identification, may usually 

 be practically confined to a description of the nymph, as the young 

 larva escapes from the egg, small, and with six legs only, but in 

 other respects generally much like the nymph, although instances 

 of difference occur, as Tegeocranus latus, described in my last paper. 



The nymph, in every instance that I have traced, changes its 

 skin three times, so that in those species where the adult carries 

 the cast notogastral skins, it carries four, viz. one larval and three 

 nymphal skins, consequently, in the species which carry the cast 

 skins, it is easy to tell at what stage of maturity the animal has 

 arrived by the number of cast skins on its back. 



The appearance of the nymph usually varies considerably 

 during the difierent stages of its growth. When it first emerges 

 from the larval skin it is usually flatter on the back than it subse- 

 quently becomes, and it is often narrower in proportion than the 

 full-grown nymph ; moreover, in the inert stage, which precedes the 

 change to the perfect creature, and also each change of skin, the 

 depressions and wrinkles, with which the back is marked in so 



* ' Deutschland's Crustacecn, Miriapoden und Arachniden.' 

 ■j- ' Uebersicht des Arachnidensystems.' 



