139 



DESCRIPTION OF ARRHENURUS SOOURFIELDI AND 

 ACERCUS LONG/TARSUS : TWO NEW SPECIES OF 

 WATER-MITES. 



By C. D. Soar, F.L.S., F.R.M.S. 



(Read April 22nd, 1913). 



Plates 12, 13. 



Arrhenurus Scourfieldi sp. nov. 



In the autumn of 1912, Mr. D. J. Scourfield handed me a tube 

 containing a few water-mites, which he had taken from fresh 

 water in Cornwall. Amongst them was one which was quite new 

 to me, a male Arrhenurus, of the sub-genus Megalurus. As I 

 cannot find that it has been described or figured, I propose to name 

 it after Mr. Scourfield. 



Arrhenurus Scourfieldi sp. nov. The specimen is a male ; 

 length 1-04 mm., greatest breadth about 064 mm. In outline 

 the body is long ; anterior corners well cut off, and slightly bent 

 inwards ; sides almost straight, tapering towards the posterior 

 margin. The posterior margin is divided by a central cleft into 

 two well-rounded portions. 



The skin is covered with small papillae ; the dorsal surface has 

 the usual indented sunk line common to members of this genus, 

 and several dermal glands both inside and outside the sunken line. 

 Looked at from above there is a small wing-like process about 

 0'15 mm. from the posterior margin. 



The colour is a dark blue-green with brown markings on the 

 dorsal surface. The epimera are slightly lighter in colour. It 

 is of the same colour as Arrhenurus globator. 



The eyes are very dark red, close to margin, about 0*32 mm. 

 apart. Capitulum, about 0"20 mm. long. 



The first pair of epimera are joined together at the back of the 

 capitulum, the second pair pressed close to first pair so that what 



