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



colours is erratic. Thus, for example, of two specimens subjected 

 to identical treatment, one may bleach out, while the other 

 retains its colours, or all or part of the dark spots may remain 

 while the rest of the colour may fade. Thor conjectures that 

 the condition of the dermal glands may have some bearing on 

 this question. The skin is rather thick, smooth and strewn over 

 with fine pores. 



The anterior maxillary processes are long and broad, tapering 

 to a point, and extend in an upward, lateral direction towards 

 the posterior, but not so far as to meet the pharynx or the 

 posterior processes. The latter have their extremities curved 

 upwards so as, in a manner, to enclose the pharynx. 



The palpi are laterally compressed, and are thinner than the 

 first pair of legs. The length varies from 04 mm. to 0*6 mm. 

 The third segment is always shorter than the second and fourth 

 segments. It should be noted that compared with the second 

 and third segments, the pores of the fourth segment are much 

 finer. These gradually disappear towards the distal extremity, 

 so that that region has a very much smoother appearance. The 

 first segment has only one short slightly curved bristle on its 

 extensor surface, where the second segment has six or seven. Of 

 these the two distal ones are long and thin, and stand back from 

 the distal extremity of the segment. The characteristic fine 

 pectinate bristle on the flexor surface is weak and not particularly 

 long, being generally about half the length of the segment or a 

 little over that. The third segment has five finely pectinate 

 bristles ; one of these is proximal and close to the second segment, 

 while another is about the middle, rather more on the extensor 

 surface than on the inner. These two are generally shorter than 

 the other three, which are distal, and about the length of the 

 fourth segment. The middle one of that three is about equi- 

 distant from the one on each side as in obscura. The fourth 

 segment has two distinct pores on its flexor surface, each with a 

 rather rudimentary hair. One of these pores is in the proximal 

 third, the other may be so far forward as to be in the distal 

 third. The five fine hairs on the extensor surface are all distal. 

 The fifth segment is small, almost conical, ending in two small 

 claws lying close together, with a small one behind them. 



The epimera agree very closely with those of insignis, with the 

 exception that the inner ends of the second pair are much 



