100 Tue Ottawa NATURALIST. [August 
forms and habits, renders them peculiarly interesting. They be- 
long, it is hardly necessary to point out, to the class Arachnoidea, 
which embraces the spiders, mites and scorpions, and includes, 
amongst other orders, the Araneina or true spiders, the Acarina 
or mites, the Poecilopoda or King-crabs, in the opinion of some 
eminent zoologists, and other interesting groups. To the Acarina 
belong the cheese-mites ( Zyroglyphus ), the parasitic skin-mites 
(Desmodex ), and others which are destitute of trachez, or 
special breathing organs, and the harvest-mites ( Zrombidium ), 
the bird- and beetle-mites ( Gamasus ), the dog- and cattle-ticks 
(Ixodes), and the water-mites (Atax, Hydrachna, &c.). The 
possession of an unsegmented abdomen united to a cephalo- 
thorax is an important feature in the mites. 
In a small vessel, containing various aquatic animals, I had 
two specimens of Hydrachna sulcata, obtained in McKay's Lake, 
Rockcliffe, in May. On 
ter, a very assiduous ob- 
server, called my attention 
to a granular mass, amongst 
some green Conferve, which 
had the appearance of micro- 
scopic pellets of a bright 
scarlet hue. Some were at- 
tached to a small twig (fig. 
3), and an adult Aydrachna 
was seated upon them, ap- 
parently in the act of de- 
positing these minute ova. 
Later in the day two other 
masses were laid, some 
being attached to the floor 
of the vessel. In all, I counted nearly three hundred eggs, and 
their brilliant colour was exactly that of the parent Aydrachna. 
After being laid, they remained slightly adhesive, as is the case 
with so many aquatic eggs, and ,became firmly cemented to 
each other and to adjacent objects, when the adhesive coat 
hardened under water. Each fegg was perfectly spherical; but, 
June 24th, my little daugh- . 
