86 NOTES ON 
They inhabit various species of confervee, and 
may often be met with in great numbers on the 
stalks and underside of healthy duck-weed 
growing on the surface of water. They are 
most numerous in April and May, and disappear 
as the heat of the season increases. They will 
not live in stagnant water containing much 
decomposed vegetation, and require therefore to 
be kept for observation in a large vessel of clean 
water. They are easily caught, after a shower 
of rain, on the under surface of the duck-weed, 
by taking a little out with a basin or cloth-net. 
When found, they appear busily engaged in 
search of prey, moving about with great activity, 
and examining every portion of the plant in the 
most scrutinizing manner. In this pursuit the 
body is not inflected, as exhibited in the mag- 
nified representation of it given in plate 9, 
figure 5, but.is kept in a straight crawling 
position. Their natural length is about the 
three-hundredth of an inch. In the drawing, 
which is the first published in this country, Dr. 
Goring has chosen the deflected position, as 
giving a more interesting view of the character 
of the animal. 
The construction of the shell is similar to 
that of the quadricornis, but it has a greater 
