12 !Mr. J. N. Iliilbeit on IrisJi Ilydrachnida. 



were five was due to the outlines of the plates not being 

 clearly visible at the time the preliminary description was 

 made. There are sixteen chitinous plates on the dorsal 

 surface, arranged as follows : — A middle series, consisting of 

 a large plate between the eyes; behind this are tiiree small 

 circular plates, arranged on each side of the middle line ; 

 and, finally, a large terminal plate, sinuate in front, with the 

 postero-lateral corners produced into pointed processes. The 

 eight marginal plates are arranged in a line on each side of 

 the body ; the most anterior of these sends forward a long 

 narrow prolongation on the outside of the eye. All of the 

 dorsal plates are coarsely areolated towards their margins and 

 more finely in the centres ; they are also very irregular in 

 outline, differing considerably on each side of the body. 



The species seems to be very local, and as I have seen no 

 reference to figures, a drawing (fig. 6) of the dorsal surface 

 is given ; the areolation of only the terminal plate is indicated. 



Localities. — Panisus Michaeli was first recorded from 

 Switzerland, where it was discovered by Dr. A. D. Michael 

 at Davos ; and Dr. Sig. Thor has recently recorded it from 

 Norway. I have also seen a specimen collected by Mr. 

 AVilliam Evans near Bolerno, Scotland, in the autumn of 

 last year. 



Thyas longirostriSf Piersig. 



This very distinct species is of local occurrence in Ireland. 

 I once found amongst Callitriche in a small pool near Ken- 

 mare many specimens, some of which were very large, 

 measuring nearly 3 mm. in length. In his paper on the 

 British species of Thyas (' Science Gossip,^ viii. p. 46) 

 Dr. George refers to the occurrence of this species in Ireland, 

 and Mr. C. D. Soar has since found it in the Norfolk Broads. 



EXPLANATION OF PLATE IL 



Fiij. 1. Momonia falcipalpis, sp. n. Dorsal view ; legs auJ palp uot 



drawn, x OO. 

 Fiy. 2. Momonia falcipalpis, sp. n. Ventral view, sliowiug structure of 



epiiuera i^-c. X 60. 

 Fiy, 3. Momonia falcijmlpis, sp. u. Terminal segment of first leg, seen 



from below, x -21. 

 Fiy. 4. Momonia falcipalpis, sp. n. Eoiirth and fifth palp-segmenta. 



X 224. 

 Fiy. 5. Arrhenurus octayonus, sp. n. Dorsal view of male. Tlie two 



pieces of the petiole are closelv approximated in the living mite. 



X 3o. 

 Fiy. G. Fanisus Michaeli, Koenike. Dorsal surface, showing arrange- 

 ment of chitinous plates. X 60. 



