ACERCUS LONGITARSUS \ TWO NEW SPECIES OF WATER-MITES. 141 



than usual, but it is the last segment of the fourth pair which 

 shows the great increase in length. The tarsi measure as much 

 as 0*60 mm., which is more than the fourth and fifth segment 

 together. 



The first leg is about 1*40 mm. in length, the second about 1*30, 

 the third about 0"90, the fourth about 1-58. 



The eyes, large and distinct, are very dark red and about 0'14 

 mm. apart. 



This mite can be most easily recognised by the length of the 

 tarsus of the fourth pair of legs. I propose naming it Acercus 

 longitarsus. 



Locality : South Devonshire (female unknown). 



There are also one or two additions to be made to British 

 records. Mr. Williamson, F.R.S.E., in working out the material 

 on the Genus Sperchon, has found that we have two species quite 

 new to the British area, and two that up to the present have only 

 been recorded for Ireland. 



1st. Sperchon clupeifer Pier. 

 Sub-genus : Hispidosperchon. 

 Locality : Oban and Norfolk Broads. 



2nd. Sperchon tenuabilis Koen. 



Sub-genus : Hispidosperchon. 



Locality : Oban. Recorded for Ireland by Halbert in Clare 

 Island survey. 



3rd. Sperchon papillosus Sig Thor. 

 Sub-genus : Squamosus. 

 Locality : Oban. Recorded for Ireland by Halbert. 



4th. Sperchon Thienemanni Koen. 

 Sub -genus : Rugosa. 

 Locality : Derbyshire. 



