39 ~4 Proceedings of the Royal Irish Academy. 



•without anv diagnosis, but Seius echinatus Koch was indicated as the type- 

 form. This seems to be an unfortunate selection for the reason that it is 

 admittedly synonymous with Seius hirswtits Koch., and Berlese had already 

 proposed the name Seiulus (1, Fasc. xli, n. 3) for the nynypha gcnerans stage 

 of that species. As a matter of fact Koch's Seius hirsutus has been selected 

 as the type species of no less than three genera, these are, Seiulus Berlese, 

 Echinoseius Bibage, and Ameroseius Berlese. 



In the following paper only two genera are made use of in the Seius 

 group, namely, Paraseius Tragardh (88. p. 432), and Seiulus Berlese. To the 

 first of these are referred three species, with the undermentioned characters, 

 for which Ameroseius italicus Berlese may well serve as a type. Tragardh selects 

 Seius mollis (Kramer) as the type of the genus, but this species belongs to a 

 different genus (Epicrius ). 



I have found three species of Paraseius in Ireland, two of these occurred 

 amongst wet moss growing on stones in mountain streams, and the third 

 (P. serratus sp. nov.) is common in very wet sphagnum, also on mountains. In 

 all probability the peculiar armature of the acetabula is an adaptation to a 

 semiaquatie habitat, as it is quite different from that of the typical Seiulus, 

 and reminds one of the ambulacra of certain gamasid mites found living 

 between tide-marks on the sea-shore. 



Seiulus spathuliger (Leonardi). 



Achill Island, not uncommon in moss, Xovember. 



The original description (39, p. 6) of this well-marked species may be 

 supplemented in a few particulars. The Achill specimens measure about 

 396m by 253m- The dorsal plate is large and has serrated margins, anterior 

 surface with granules which tend to form short transverse ridges ; hairs ornate, 

 those of the hinder part of the plate are broad, with a median keel and deep 

 pectinations, the last three pairs of the marginal series are strongly clavate 

 and stand out conspicuously from the end margin of the body ; the latter is 

 distinctly crenulate. Yentro-anal plate completely covering the epigastric 

 region, the hinder part of the shield is granulated. Tritosternum feebly 

 developed with two pairs of lateral spines close to the filaments. The 

 peritreme is strengthened by a porous shield, and its canal lies close to the 

 acetabula. 



Capitulum rather short and broad; epistome trispinous. Fixed chela 

 with four teeth almost equidistant from one another, and there are two teeth 

 on the free chela. In his description of the jaw armature Leonardi evidently 

 includes the apical tooth, as he mentions one more tooth for each chela. 



