548 BRITISH OmBKTlDM. 



The Tectopedia are also entii'ely absent, tliey are 

 not in any way required, and indeed their presence 

 would be inconsistent with the general construction 

 of the animal. 



The Legs are very differently arranged from what 

 is usual in the family. They seem, when viewed from 

 the side, as if they were all inserted together, almost 

 in a bunch, the fourth pair being nearer to the median 

 line of the body than the third pair, but scarcely set 

 further back (fig. 2) ; this arrangement is appropriate 

 for enabling them to be withdrawn into the shelter of 

 the carapace, and to escape the anterior edge of the 

 genital plates. They are more or less cylindrical and 

 curved, but are more clinging and crawling than 

 walking or running organs ; this is doubtless explained 

 by the wood-boring habits of most of the species. The 

 COX86 are usually small joints, the femora considerably 

 the largest, the genuals and tibife of about equal 

 length, the tarsi longer and somewhat conical. The 

 distal joints are generally abundantly furnished with 

 long setiform hairs, and the tactile hairs on the ante- 

 rior legs are very large. The claws are monodactyle 

 in all British species which I am acquainted with 

 except H. ardua, where they are tridactyle. In the 

 monodactyle species the claw is usually of remarkable 

 size, sometimes not very much shorter than the 

 tarsus ; it is usually somewhat open in the curve, and 

 considerably thickest in the middle. 



The Abdomen is exceptional in form, it is almost 

 egg-like ; this arises from the fact that the depth from 

 dorsal to ventral surface is as great as, or in some 

 foreign species {e.g. H. arctata, which Murray says he 

 found in England, but I have not been able to verify 

 the species), much greater than, the width from 

 side to side; and that the notogastral plate, which 

 always maintains its rounded form, is sufflexed largely 

 on to the ventral surface at the sides, and usually, 

 although not invariably, behind, so that the opening 

 for the ventral plate is very small ; and it is wholly or 



