482 BRITISH ORIBATID^. 



rostral hairs are usually rather thick, sometimes 

 curved, sometimes short and diverging. 



The Labium is generally short and broad, often 

 with a small median point (PL XLVII, fig. 2). 



The Epistome, instead of being a mere thin edge, as 

 it is in Orihata, JYotasjns, &c., and indeed in most 

 genera, becomes, in some species of this genus, widened 

 out into a broad expansion, so that the labium does 

 not occupy above half the width of the portion of the 

 cephalothorax in which it is situated (PI. XLY, fig. 2 ; 

 PI. XLVII, fig. 2). This produces, in many species, 

 the sudden widening of the cephalothorax behind the 

 rostrum (JSf. horridus, N. hivernicatus, N. sjjiniger) ; and 

 this, being followed by a deep indentation for the 

 insertion of the first pair of legs, gives a somewhat 

 hammer-headed appearance to the cephalothorax. 



The Palpi. — Nicolet states that in Nothriis the first 

 joint of the palpus is the longest ; he figures it so in 

 his drawings ; this would be quite exceptional in the 

 Oribatidce, but I am not able to confirm this observa- 

 tion. The small first (basal) joint seems to me to be 

 present as usual, but in the typical species to be very 

 small indeed; it is true that in such species as N. 

 spiniger the portion of the labium from which each 

 palpus springs is folded over so as to form an almost 

 tubular support for, or continuation of, the palpus. 

 Probably Nicolet regarded this as the first joint, and 

 missed the small ordinary first joint, from its being 

 minute and almost wholly sunk in the before-named 

 tube ; but if this tube were to be regarded as the first 

 joint the palpi in all the Oribatidce would have to be 

 considered as six-jointed, with the first joint anchylosed 

 to the labium, but I do not think that this has ever been 

 asserted, nor do I think that it could be maintained. 

 The palpus is generally almost cylindrical, but some- 

 times {N. theleproctus, N. sylvestris, &c.) the second joint 

 is considerably enlarged ; it is usually the longest. The 

 terminal (fifth) joint is often furnished with strong 

 papilljB, or even almost bifid (PI. XLY, fig. 7 ; N. 



