FOUND IN NORTH WALES. 49 



strong teeth or setae arranged like the teeth of a comb on the 

 inner curve of the foot. (In Pionacercus leuckcvrti there are only 

 seven.) These teeth do not appear under the microscope to be 

 always placed exactly in the same position on the inner curve of 

 the foot, but I think the difference in the position can be ascribed 

 to the twist which the foot may have derived from the pressure 

 necessary for examination. In Fig. 3, for example, it will be 

 seen that the three teeth nearest the body are placed more back- 

 ward than the rest, but on the opposite foot of the same mite the 

 teeth appear to be all in a gently curved line. There are two 

 more of these setae near the end of the curve, and another on 

 the clubbed portion of the foot, as shown in Fig. 3, These may 

 answ^er the purpose of claws, but they do not appear sufficiently 

 strong for that j^urpose. 



Epimera. — These are in one piece covering the greater part of 

 the ventral surface like a shield. This is hard and chitinous and 

 is of the same colour as other parts of this mite, namely, an 

 orange- yellow. 



Paljn. — These are about 0'18 mm. in length, each composed 

 of five segments of which the second and fourth are longer than 

 the others. The fifth segment is like a finger. There is a small 

 peg on the inner edge of the palpi (Fig. 4) springing from near 

 the end of the fourth joint and slightly overlapping the fifth 

 segment. This is the usual feature in all species of Pionacercus 

 and Piona. 



Description of Female. Oval in form. Length about 

 0*64 mm., breadth about 0'50 mm., same colour as male. The 

 much larger size of the female as compared with the male wdll 

 be seen by a glance at Figs. 2 and 5, which are both drawn to 

 the same scale. The fourth pair of legs have the greatest number 

 of swimming hairs. They show no trace of the peculiar modifica- 

 tion of the terminal joint found in the male. The only difterence 

 between this animal and the female of Pionacercus leuckarti is 

 that the epimera cover a larger portion of the ventral surface, 

 and that the palpi are thicker and stronger. 



On account of the somewhat unusual shape of the male I 

 propose to call this species Pionacercus pyriforr^iis. 



JouRN. Q. M. C, Series II.— No. 48. 4 



