FIG. 3. CANTHOCAMPTUS MINUTUS. 40 DIAMETERS.
They are found abundantly in ponds and ditches, and in salt water. Sometimes they are so abundant in drinking water that has not been filtered, as to alarm a timid person, but you will find them just as good to eat raw as they are cooked. The most common of these little creatures is the Cyclops Quadricornis, so called because he has one eye and four horns. (Fig. 2.)
FIG. 4. CHYDORUS SPHŒRICUS.
50 DIAMETERS.
This picture represents a female, and she carries her eggs in the two little black bags that you see fastened on each side of the abdomen. You will find it very interesting by and by to watch the eggs hatch and see the little cyclops hop away. When young they do not look much like their parents; they are rounder and their legs are more prominent. The female cyclops (the male is comparatively rare) is the most common creature in Cochituate water, and as it is constantly eating, it helps to purify the water, and, in its turn, is eaten by the fishes.
In swimming it contracts its four horns and its fringed feet with a quick movement that throws it forward through the water with a leap.
Its one eye is of a brilliant red, and is a beautiful object under the microscope. The shell also is sometimes beautifully colored, and is often transparent, so that the internal organs are plainly visible through it.
Another of the family of Cyclopidæ is the Canthocamptus minutus (fig. 3), which you see is longer and more tapering in its form than the Cyclops Quadricornis. It is also very common and very active.
Chydorus Sphœricus (fig. 4) is a very pretty round form interesting to study when transparent.