39 28 Proceedings of the Royal Irish Academy. 



Feltria Rouxi Walter. (Plate III., fig. 30 a-b.) 



Amongst aquatic mosses in a stream on the lower slopes of Croagh- 

 patrick, at Hurrisk, County Mayo, July. 



The female of F. Rouxi was described by Walter from Swiss specimens, 

 and apparently the male was unknown. A description of it, with figures, is 

 given in the present paper. 



The colour of this mite is pale yellow, with black pigmented eyes. In the 

 female, the dorsal surface is occupied by a large shield, which projects 

 between the eyes, much as in the ? of F. circularis; but the small anterior 

 separate plates present in that species are wanting, and there are only two 

 small circular plates placed behind the dorsal shield instead of the three 

 found in F. circularis. The posterior marginal cleft is similar to that of 

 F. uivscicola $ , and there is a large anal plate. The antenniform bristles 

 spring from well-developed frontal prominences, and are usually directed 

 towards the sides of the body. 



The male of this species occurred on Croaghpatrick. 



It is considerably smaller than the female, measuring only - 286 mm. in 

 length by "253 mm. in breadth. The appendages are much stouter. It 

 differs from the males of the described species in having the dorsal surface 

 almost entirely covered by a well-developed chitinous shield (PL III., fig. 30 a), 

 with the exception of an extremely narrow marginal rim, in which are placed 

 the prominent hair-bearing papillae. This plate shows the coat-of-mail 

 sculpture so characteristic of some genera of Hydracarina. About half way 

 between the middle and the sides of the body, on each side, there is a row of 

 small hair-bearing glands The end of the body is double-margined, the upper 

 ledge carrying two papdlae. 



The arrangement of the epimera is very similar to that of the allied 

 species. The processes of the first two pahs are rather long, and the outer 

 margins of the fourth pair are strongly sinuate. The sub-cutaneous margins 

 are separated by a very narrow space in the middle line. 



The male genital plate resembles that of F. muscicola, except that the 

 front margin is not pointed in the middle : and, judging by Piersig's figures, 

 the hinder margin is not so deeply cleft. The number of genital-discs varies. 

 In the Croaghpatrick specimen there are about twenty-two on each plate. 



The legs are remarkably stout, much more so than in the female. The 

 secondary sexual structure, found on the last segment of the third pair of legs, 

 consists of three modified spines placed close together on the swollen ventral 

 margin of the segment (PI. III., fig. 30 b). 



The palps are short, and a little stouter than the first pair of legs. Length, 



