140 C. D. SOAR, DESCRIPTION OF ARRHENURUS SCOURFIELDI AND 



is known as the first two pairs of the epimera form one distinct 

 group. 



The posterior pair are in two distinct groups placed about 

 0*05 mm. behind the second pair. 



The genital area lies about 0*08 mm. behind the fourth pair of 

 epimera, the plates stretching the whole distance across the 

 body of the mite. The length of each plate is about 0*25 mm., 

 tongue shaped and covered with numerous acetabula. 



The legs are of the usual structure of the genus with the spur 

 on the fourth segment of the fourth leg. They are strong and 

 well provided with swimming hairs. The first leg about 0"60 mm. 

 long, fourth leg 0'84 mm. 



Locality : Near the Lizard, Cornwall, 1912. Female unknown. 



Acercus longitarsus sp. nov. 



Acercus longitarsus sp. nov. The body is 0*76 mm. in length ; 

 breadth about 0'54 mm., ovate. The colour is a pale straw 

 yellow with dark-brown markings. There is a reddish-yellow 

 wedge-shaped patch in the centre of the dorsal surface. 



The epimera cover nearly the whole of the ventral surface, and 

 differ from that of the type species Acercus omatits in the follow- 

 ing important particulars. Firstly, the genital area instead of 

 being situated in a small bay on the posterior margin of the 

 epimera as in Acercus ornatus, is partly enclosed in an angular 

 space formed by the posterior edge of the epimera being turned at 

 a low angle towards the median line. Secondly, near the base 

 of the epimera are two small incurvations, one on each side, which 

 are not found in the type species of this genus. They run into 

 the epimera about O05 mm. The actual genital area itself is 

 similar to type species, having six acetabula arranged in the same 

 way. 



The palpi are about 0*45 mm. in length. On the flexar edge 

 of the fourth segment are placed two long hairs, a little distance 

 apart ; they are close together in Acercus ornatus. 



The legs of the species form the most striking departure from 

 the type form and in fact all other species of this genus ; on 

 comparison it will be seen that the tarsi are enormously developed 

 in length. 



The last segment of the first and second pairs of legs are longer 



