39 36 Proceedings of the Royal Irish Academy. 



A preliminary description of this mite appeared in the " Zoologischer 

 Anzeiger" some rears ago 5 . The species is allied to Arrhenurus solidus 

 Piersig, hut may be easily recognized by the shape of the appendage and other 

 characters. A short description of the female is given in the present paper. 



The colour of the type-specimens Baheny Pouds, County Dubhn) is 

 noted as greenish-yellow, with brown dorsal markings, and the legs are 

 yellow. Length, including the appendage, slightly over one millimetre. 



Compared with A. solidus the body is longer and not so strongly narrowed 

 towards the front margin, where it is truncated in outline. The chief 

 difference is in the shape of the male appendage, which is longer, narrower, 

 and much more distinctly marked off from the body than it is in that species. 

 A small petiolus structure, which appears to be forked at the extremity, is 

 placed near the middle of the appendage. The dorsal groove is strongly 

 narrowed in front and encloses a larger area of the back. The epimera are 

 much as in A. solidus, fourth pair rather strongly angled at the middle of 

 the posterior margin. 



The palps measure about 32 mm. in length. In side view the distal 

 extremity of the second segment is armed with a long spine, and on the inner 

 side there is a small group of long stout spines. The sword-bristle on the 

 inner side of the fourth segment is short and sharply pointed, and in the 

 G-alway specimen barely reaches to the end margin of the segment. The legs 

 are decidedly longer and more robust than in A. solidus Piersig, last pair 

 devoid of a spur. 



The female (PI. III., fig. 25 e) is a little shorter than the male; the actual 

 length is 1"05 mm. The body is of a regular oval shape, resembling in this 

 respect the ? of A. Stecki Koenike (" Deutschlands Hydrachniden," Taf. xxxvL, 

 fig. 95 b), but more oblong. The plates of the genital area are very broad 

 at the base, and narrow rapidly towards the free end. The delicate plates 

 protecting the orifice are without ehitinous thickenings (" chitinflecke " of 

 Koenike . 



localities. — A male and female of this species occurred amongst refuse 

 taken from a bog-pool on Cartron Mountain, County Galway, in the month 

 of March, by Mr. S. W. Kemp : ponds at Baheny. County Dublin, April ; 

 and a female example has been found in bog-pools near Bundoran, County 

 Donegal, in the month of September. Mr. C. D. Soar has met with it in 

 England. 



Arrhenurus ornatus George. Plate III., fig. 27.) 



Achill Island, frequent in bog-pools and lakes, June. 



A common and widely spread mite in Irish, as well as in British waters 



