In a former chapter we have described an interesting relation of the Vorticella, the Cothurnia, whose elegant crystal vases form a very artistic abode, characterised by possessing a distinct foot. Other species of the same family inhabit vases which have no foot or stalk, or live in gelatinous sheaths less accurately fashioned. Sometimes these creatures are obliging enough to conform to the specific descriptions which eminent naturalists have given of them, and also to the characters which the authorities have assigned to the different genera in which they have been grouped, but the microscopist will often meet with difficulties in the way of classification. [Illustration: Vaginicola (?) (A, elongated; B, retracted.)] Attached to a piece of weed were a number of cylindrical masses of brownish jelly, with rounded tops, and situated in an irregular and very transparent sheath, about twice as high as themselves. Presently they all rose up to four times their previous height, put forth a beautiful crown of vibrating cilia, and opened a sort of trap-door to their internal arrangements. In this position they had a long cylindrical form, gracefully curved, but of nearly equal width from the mouth to the base, and they readily imbibed particles of carmine, which tinged sundry little cavities with its characteristic hue. The slightest disturbance caused the ciliary wreaths to be drawn in, and the bodies to be retracted, and descend into their house like a conjuring toy, until the appearance first described was reproduced. The general form and structure of these objects was like the drawings usually given of _Vaginicola_, which is said not to exist in groups, although two individuals are commonly found in one well-shaped cell. These creatures, however, did not taper towards the base as Vaginicolæ generally do, and perhaps they became aware of this defect in their figures, for after a day or two a change appeared, and they assumed a more graceful form by swelling out in the middle, and then growing slender down to the bottom, very much like the pattern given by glass-blowers to little vases of flowers. It is very important to note the changing appearance of animalcules, and where the same individuals can be observed from day to day, these will often be found considerable. It is probable that when such particulars are fully known, the number of species will be greatly reduced, and the study of these organisms considerably simplified. I have called the animals just described _Vaginicolæ_, but the reader must be prepared to find similar bodies, inhabiting well-formed vases, either solitarily or in couples, the latter condition arising from the fission of one individual without a corresponding division of the abode.