266 



front, and strongly narrowed posteriorly. The skin is closely studded 

 with conical papillae, but when highly magnified these appear almost 

 triangular in shape, presenting an obscurely serrated appearance if a 

 portion of the skin be examined in outline. At a distance of 0,8 mm 

 behind the eyes, on each side, there is a curved chitinous plate (fig. 1 a) 

 which is strongly concave on its inner margin; about midway between 

 these plates and the paired eyes there are two small oval depressions 

 in the skin, but these are not chitinous, and are no doubt muscle 

 attachments. The epimera are comparatively large and sharply pointed 

 at the inner angle of the fourth pair'; outside of this the subcutaneous 

 process is strongly recurved. The genital area (fig. 2 a) measures 

 0,76 mm in length, by 0,66 mm in breadth, resembling that of H. 

 Pier sigi Koen., in structure, but besides a decided difference in outline, 

 the anterior cleft is narrower and tapers inwards to a sharp point; 

 genital opening rather quadrate containing two blade-like hyaline 



Fig. 1. 



Fig. 2. 



Fig. 1. Hydrachna incisa n. sp. <$ Anterior right hand margin seen from above; 

 a, chitinous plate; 5. muscle attachment forming depression in skin — not chitinous; 



c, paired eye. 

 Fig. 2. a, Genital area of male; b, Third an fourth epimeral plates. x31. 



organs which meet at their points; apex densely clothed with white 

 hairs. 



The palps are about 1,68 mm in length, the outer margin of the 

 second segment is irregular in outline bearing a number of fine short 

 hairs, and nearly equals the third segment in length, otherwise the 

 palps resemble those of H. Piersigi (Deutsch. Hydrach. Taf. L, 

 fig. 181a). Rostrum about 2 mm in length, gradually curved in out- 

 line. Legs robust, length of the first pair about 2,4 mm, of the fourth 

 3,8 mm, well supplied with long swimming hairs. 



Locality: An adult male of this mite was sent to me alive by 

 Mr. Dudley Westropp who took it in a pond near Carrigaline County 



