4-30 DESCKIPTION OF A MITE 



founded, resembles Trachynotus pyriformis (Kramer) 

 more closely than it does any other recorded species. It 

 is, however, decidedly different, and is characterised by 

 the squareness of its abdomen, the thickness and rough- 

 ness of its chitinous dermal skeleton, and especially by 

 the powerful chitinous ridges or wing-like expansions 

 on the lateral surface between the second and third pair 

 of legs. 



Length, ~$ and ? , about '95 millim. 

 Breadth " " -55 " 



The abdomen is almost square, but somewhat longer 

 than broad, and slightly narrowed at its junction with 

 the cephalothorax, from which it is not plainly dis- 

 tinguished. The extreme edge is a strong chitinous 

 ridge bordered with a thick fringe of short, stout, 

 curved ha'irs, as in T. pyriformis. The dorsal surface 

 of the cephalothorax is also narrowed towards the front, 

 and has a curved anterior margin bent down so as to 

 protect the mouth, as in that species ; it bears a few of 

 the same kind of hairs as the abdomen, and has a chiti- 

 nous thickening at each side. The abdomen rises almost 

 perpendicularly from the marginal ridge. There is a 

 central depression occupying the posterior half, or rather 

 more than half of the abdomen ; and at the bottom of 

 this depression are transverse ridges, the hinder ones 

 nearly straight, and the anterior ones bent in the mid- 

 dle, the central point being forward ; at the sides of, but 

 not in, this depression, are two chitinous blocks which 

 seem to form a starting-point for the ridges. Anterior 

 to this depression the central portion of the creature, i.e. 

 its longitudinal dorsal axis, is higher in level than in 

 parts nearer the margin, and forms an irregular triangle 

 of rough chitine. A broad chitinous plate or ridge pro- 

 jects on each side above the second leg, and between 

 that and the third, evidently for their protection ; it is 

 probably flexible at the will of the creature, as in the 

 genus Oribates. 



