CLASSIFICATION. 591 



vegetable feeders ; finally, Nicoletia does not look at 

 all like one of tlie Oribafldce. 



The other genera constitute the group called Tarso- 

 nemidce by these writers ; it will be seen that Canestrini 

 does not include this in the Oribatidai ; he has not yet 

 reached it in his ' Prospetto dell' Acarofauna Italiana,' 

 but in the earlier ' Intorno agli Acari Italian! ' he 

 treated it as a separate family, which seems to me 

 correct, unless it be joined to one of the other small 

 groups; it certainly does not appear that there are 

 any grounds for classing it as a sub-family of the 

 Orihatidce. The idea did not first arise with Berlese ; 

 Haller appears to be responsible for it, as he puts 

 Pygmejjhorus, Kramer, at the end of the Orihatidce. 

 Haller did not pay special attention to the Orihatidce, 

 and his reasons for including Fygmeplwrus therein 

 were, firstly, the supposed presence of a tectum in 

 each, which really does not exist nor even appear to 

 exist in Pygmephorus ; but there is some reason to 

 suppose that Haller did not fully realise what Nicolet 

 meant by a tectum ; secondly, the presence of an organ 

 bearing a resemblance to the pseudo -stigma and pseudo- 

 stigmatic organ of the Orihatidoe ; the existence of this 

 organ (both in Pygmephorus and Nicoletia) appears to 

 me to be the only argument of any importance for 

 including them in the Orihatidce, and when these organs 

 were supposed to belong to the respiratory system, and 

 to indicate its nature, it was apparently of value, but 

 now that it has been ascertained that in the OribatidcE 

 they are not connected with that system and do not 

 indicate its nature, it would indeed be slender grounds 

 for including in that family creatures which in all other 

 respects are entirely unlike ; and even these organs, 

 although having some resemblance to those of the 

 Orihatidce, are yet very different, and are not in a 

 similar position. 



The whole structure and organization of the Tarso- 

 nemidcB is quite different from that of the Orihatidce ; 

 their life-histories and habits are also entirely different. 



