278 CD. SOAR ON THE GENUS HYDRACHNA. 



5. Hydrachna scutata, Pier. 



Female : length about 3*4 mm. Common in Britain. Mr. 

 Halbert records it from Ireland. It can be identified by the 

 form of its dorsal shield (Fig. 8). This plate is not always so 

 well formed as in the particular specimen from which this figure 

 was drawn, sometimes being very irregular in outline. The skin 

 is covered with pointed papillae, and the chitinous skin of the 

 dorsal plate is very finely granulated. The median eye is very 

 plainly visible on the plate between the pair of eyes. 



6. Hydrachna eruenta, Mull. 



Male about 2 mm. This is the type species of the genus, but 

 it is not at all a common species with us. I give a figure of 

 the dorsal plate (Fig. 9). This specimen was taken in the 

 Warren, Folkestone. 



7. Hydrachna conjecta, Koen. 



Male about 25 mm. in length, very light red in colour. Plate 

 narrow and ribbon-like (Fig. 12). Already recorded from England 

 and Ireland. 



8. Hydrachna dissimilis, Halbert. 



Male about 3 mm. This beautiful mite was found in Ireland 

 and described by Mr. Halbert. It was taken in a brackish 

 ditch on the coast of County Wexford. The skin is covered 

 with rounded scale-like papillae. The genital plate of the 

 female has four unusually large acetabula across it, that of the 

 male having two, one on each outer edge. 



9. Hydrachna globosa, de Geer. 



Female about 3 mm. long. Male about 2 5 mm. This is 

 rather a common mite in Britain, having been recorded from 

 England, Scotland, and Ireland. The skin is covered with 

 rounded papillae (Figs. 1 to 5, and 11). 



