512 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA : 



bristles on its inner side, one of these being nearly proximal and 

 the other two almost distal, one of them being on the extensor 

 surface and the other just inside of it. The fourth segment has 

 three fine hairs distal on the extensor surface, and two fine pores 

 close together on the flexor surface as in the imago. 



The epimera are relatively short and broad. The area between 

 the fourth pair of epimera is relatively wider than in the imago, 

 but the fourth pair itself is much narrower, so that the 

 gland pores lie well outside. The inner ends of the second pair 

 are much broader, while the inner ends of the fourth pair are 

 cut away very obliquely. The provisional genital area lies about 

 half-way beyond the epimera. The outer ring is rather more 

 oval than round and has only four minute pores. The sclerite 

 between the genital area and epimera lies close up to the epimera. 

 The anal ring is broad but not strong. 



The legs have no swimming hairs, though a single long hair at 

 the distal end of the fifth segment of the fourth pair of legs may be 

 observed. The first segment of the fourth pair of legs differs from 

 the corresponding segment in the nymphs of other sub-genera in 

 the possession of three bristles on the extensor surface. 



Lebertia trisetica Sig Thor. 

 (Sub-gen. Hexalebertia.) 



1907. Lebertia trisetica Sig Thor. Zool. Anz., xxxii. 157, fig. 91. 



This form is allied to L. stigmatifera, but in comparison with 

 it trisetica will be found to possess a thicker skin, the ridges on 

 which are stronger and broader, with a greater tendency to 

 branching. The intervals between the ridges are broader and 

 minutely porose. So far as can be judged from preserved 

 material, the colour would appear to be a reddish brown with a 

 tinge of yellow. 



In outline the body is oval or elliptical, with a length of about 

 0*9 mm. and a breadth of about 0*7 mm. Between the antenni- 

 form bristles the anterior margin is weakly concave. 



The capitulum is about 0*21 mm. in length, with the lateral 

 processes of moderate length and pointing in an antero-lateral 

 direction. 



The palpi are relatively slender, and are a little over 0*4 mm. 

 in length, the individual segments being about 0*035, 0*102, 



