214 Wisconsin Academy of Sciences, Arts, and Letters. 
caudal appendix has pronounced lateral projections and a clearly 
defined hyaline appendage. The petiole is conspicuous; the sides 
roll over dorsally to enclose a central oblong structure arising 
out of it. 
The palpi are stout, with a few large bristles. The fourth joint 
of the fourth leg has a well defined thumb-like projection. The 
color of the new species is dull red with indistinct brown areas 
where the internal organs show through the body wall. The legs 
have a greenish tinge. The total length is 1.15 mm., the greatest 
width, 0.9 mm. 
Arrhenurus elongatus nov. spec. 
PI. VII, fig. 6, 7; PL VIII, fig. 14, 15 
It is a pleasure to be able to record the finding of a new species 
of Arrhenurus from Alaska, the first account of any work on the 
water mites from this territory that the author is aware of. Quite 
appropriately this species comes from the old Russian town and 
former capitol, Sitka. ^ It was found in the border of a small shal¬ 
low pond choked with yellow pond lilies and like plants, in a boggy 
meadow near the town. With it were a few individuals of other 
genera, the species not yet determined. 
A. elongatus is a large mite belonging to the subgenus Megalura- 
carus. It is 1.5 mm. long, with a width of 0.73 mm. It resembles 
A. solifer Marshall and A. pseudoconicus Piersig, both American 
forms, and A. conicus Piersig, a European species. In this group 
of related species the appendix narrows conspicuously at the end. 
The new species, however, is more slender and has a more elongated 
appendix than in any of the nearly related species, a feature so 
characteristic that it has suggested the specific name. 
Only one individual, a male, was found. The body is widest 
and most elevated in the anterior half; likewise, the appendix is 
largest in the proximal half, though constricted where it joins the 
body. The end of the appendix is bowed out and has several small 
humps and hairs, as shown in the figures. The three groups of the 
epimera are close together; the first and second pairs of plates have 
sharp projecting anterior corners, and the fourth epimera are 
very wide. The genital area is small and does not project beyond 
the body wall. The color of the animal is dull red. 
