566 IVAR TRAgARDH 



took them for such until the boihng of one specimen in lactic acid convinced 

 me of my mistake. 



It is of great interest that Berlese describes the legs of P. ornatissimus 

 as »laciniati» and writes of P. rotundatus: »Corpus et pedes pellicula pellucida, 

 rugulosa inducta» (1. c. p. 96). 



One of the most astonishing features of the genus is, however, the arti- 

 culation of the legs, which, as far as I know, is unique amongst the Oribatei. 

 As a rule, whenever there is a condylus developed which turns in a socket, 

 the condylus is to be found at the basal end of the distal joint, the socket 

 being furnished by an excavation and a collar-shaped structure of the proximal 

 joint. In the species from Juan Fernandez, however, the socket is found at the 

 basal end of the distal joint which embraces the distal end of the proximal 

 joint. This applies to the articulations between femur and genu, genu and 

 tibia, and tibia and tarsus (figs. 28 — 30). 



Berlese does not mention anything about this peculiar feature in any of 

 the four species described by him, but fortunately his drawing of P. rotundatus 

 is so exact (1. c. fig. ']6, pi. 7) that we are able to see planly that at least 

 between the femur and genu there is the same kind of articulation. We must 

 assume that the other species of the genus have the same structure. 



The remaining features of the genus Plateremceus may conveniently be 

 discussed after the description of the new species. 



Diagnosis: Hysterosoma broadly rounded, flat or adpressed, cov- 

 ered by thin, reticulated larval and nymphal shields, the centre of 

 which is in front of the middle and which are easily detached. Cu- 

 ticle areolated and covered by a thick layer of secretion. Inter- 

 lamellar hairs very small, lamellar hairs inserted near anterior mar- 

 gin of rostrum. Tectopedia I present, horn-shaped. Femur, genu 

 and tibia articulating in sockets of resp. genu, tibia and tarsus. 

 Three claws on a peduncle. 



Systematic position of Platereniaeus. 



When endeavouring to ascertain the systematic position of PlateremcBus 

 one of its chief characteristics, the presence of the larval and nymphal skins 

 does not give us much aid, because this feature appears independently in 

 several families, which are not closely related, as in NeoliodidcB, DamcBidcB and 

 DameosomidcB (LicneremcEus). Nevertheless it seems evident that Plateremceus 

 is related, although distantly, to the subfamily Neoliodincs of the family Neo- 

 liodidcB. 



I draw this conclusion from the examination of a new species of Platere- 

 mceus from South Africa, which as regards the shape of the exuviae resembles 

 Platyliodes but at the same time has the articulation of the legs peculiar to 

 Plateremeus vestitus and in other respects resembles P. rotundatus. 



I have been able to examine Platyliodes and have abundant material from 

 Neoliodes both from Juan Fernandez and from South Africa and have thus 



