I904- H ALBERT. — Sligo Conference, Acarinida. 201 



Dlplodontus desplclens (Miill).— Lakes at Rosses Point, 



Hydryphantcs ruDer (De Geer). — Lakes at Ballysadare. 



Arrhenurus sccurlformis, Piersig. — In pools on the shores of 

 Lough Gill. A rare species usually occuring singly.. 



Arrhenurus lYIoebiiy Piersig. — We were fortunate in securing this 

 species, an addition to the list of British Water-mites, in pools on the 

 shore of Lough Gill near Rockwood. A. Moebii (fig 3), belongs to the 

 long-tailed division (sub-genus Megahirus) of the Arrhenuri, of which 

 we have about twelve species recorded from Britain. It differs 

 strikingly, however, from all of these. Characteristic of the species are 

 the two small hyaline processes which project beyond the apex of the 

 body appendage in the male ; immediately over these is seen a small 

 sharply-pointed petiolus. Anterior to this again is a small prominence 

 surmounted by a semicircle ridge, and a small rather obscure mark, 

 shaped like an inverted crown. All of the characters agree excellently 

 with Dr. Piersig's description, except for the absence of a pair of long 

 hairs on the end margin of the body -where there should be a pair on 

 each side. These hairs, however, are easily broken off. The body 

 appendage also is rather wider at the base than in Piersig's figures.'' 



A. Moebii was discovered about five years ago by Dr. R Piersig in a 

 lake (Kaltenbach See), in the Black Forest, and so far as I am aware the 

 present is the second recorded occurrence of the species. It may well 

 prove to be a lake-frequenting mite, of which we have at least one other 

 species— -(4. Kami —vfhich. inhabits certain lakes in Ulster, and would 

 seem to be a fairly deep-water form. 



IVIIdeopsIs orbicularis (Mlill).— Glencar Lake. 



Lebertia sp. — Specimens of at least two species oi Lebertia, yet to be 

 identified, were taken in streams near Ballysadare, and in Lough Gill. 



Sperchon sp.— A Sperchon, closely resembling S. glandulosus, Koen., 

 or perhaps some allied species, occurred amongst aquatic plants in a rapid 

 stream near Ballysadare. 



Litnnesia histrionica (Herm.) ) Common in Lough Gill, and in 



Limncsia maculata (Miill.) j lakes at Rosses Point. 



Hygrobates retlculatus (P. Kram.) — Ballysadare, and in Glencar 

 Lake. 



H. longlpalpis (Kerm.)— Lough Gill. 



Atax crassipcs (Miill.)— Lough Gill. 



Fiona conglobata (C. L. Koch.)— Lough Gill. 



Fiona nodata (Miill.)— Glencar Lake. 



Fiona rotunda (P. Krara.) — A varietal form of this species is abundant 

 in Glencar Lake. The genital field is larger than in the type form, and 

 carries a greater number of discs (35 to 40). In this respect it is inter- 

 mediate between P. rohinda and P. disparilis, Koen. The palps are of 

 robust build, bearing three well marked pegs at the end of the fourth 

 segment. The type form is, however, very variable. 



1 " Deutschlands Hydrachniden," pi li., figs, ii^a—d. 



