The Melicerta is, however, an awkward object to undertake to show to our friends, for as they knock at the door she is apt to turn sulky, and when once in this mood it is impossible to say when her fair form will reappear. At times the head is wagged about in all directions with considerable vehemence, playing singular antics, and distorting her lobes so as to exhibit a Punch and Judy profile. When these creatures die they leave their tubes, which are often found empty in the ponds they frequent. The Melicertas are conveniently viewed with a power of from sixty to one hundred linear, and a colony of them may be kept alive for some weeks in a glass jar or tank. Among the remainder of my tiny captives were two beautiful members of the Vorticella family, _Epistylis_ and _Carchesium_. The reader will remember that in the Vorticella previously described, the bells stood upon stalks that were very flexible, and retractile by means of a muscle running down their length. The _Epistylis_ is, as its name imports, the dweller on a _pillar_. The stem is stiff, or only slightly flexible, and has no apparatus by which it can be drawn down. The specimen mentioned stood like a palm-tree, and the large oval bells drooped elegantly on all sides, as its portrait will show. At times they nodded with a rapid jerk. [Illustration: Epistylis.] The _Carchesium_ differs from the common _Vorticella_, by branching like a tree, but the stems are all retractile, although the trunk seldom exercises the power. A group of these creatures presents a spectacle of extraordinary beauty--it looks like a tree from fairy-land, in which every leaf has a sentient life. In general structure the bells of the _Epistylis_ and the _Carchesium_ resemble the common _Vorticella_, and like them may be seen with a power of about one hundred linear for general effect, and with a higher one for the examination of special points. Pritchard notices three species of _Carchesium_, and eighteen of _Epistylis_;[13] some of which it is to be hoped will turn out to be only varieties. [13] An interesting _Epistylis_, called _Digitalis_, from its bells resembling fox-glove flowers in shape, occurs as a parasite upon the _Cyclops quadricornis_, a very common entomostracan in fresh-water ponds. At this moment I have a beautiful specimen, branching like a bushy tree, and attached to the tail of a _Cyclops_, who can scarcely move under his burden, which is like Sinbad's "Old Man of the Sea." Towards the end of this month rotifers abounded, and polyps were plentiful. Among the rotifers was one about a two-hundredth of an inch long, protected by a carapace, and having a tail terminating in a single style, hence called "Monostyle." There is perhaps no class of creatures that present so many curious and unexpected forms as the rotifers; and although we have noticed a good many, there are far more that remain to be found and described.