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There is a family of Infusoria closely allied to the Vorticellæ; In their form and habits, but distinguished by the absence of a stalk and by the possession of a roomy sheath resembling a very thin transparent vase, into which the animal can withdraw itself by a general contraction of the whole body. The two kinds with which I um acquainted are Vaginicola and Cothurnia. The sheath of the former is sessile; that of the latter is supported on a short stem. They multiply by self-division. Hence they frequently occur in pairs, each pair occupying a common vase. From the vase the twins protrude their ciliated crests by a simultaneous impulse, and after feeding awhile suddenly close up and shrink to the bottom of their cell. The retreat, however, is only momentary. Immediately they begin to rise again slowly and steadily, until they once more stretch forth to fish for prey, A contractile vesicle is situated not far from the mouth. The sheath of Cothurnia may be yellow. brown, or sty red. I have seen Vaginicola sailing about, case and all, attached to a fragment of weed. Both kinds continue active through the winter.

During the early part of the year 1873 I had frequently washed the boulder clay of Cheshire for Foraminifera, without success, until in September of that year my friend, Mr. J. B. Manning, (Governor of Chester Castle,) found in the upper boulder clay of Newton-by-Chester a boulder bored by Saxicava rugosa, in the cavities of which fragments of the shells remained. Wishing to possess these fragments, he proceeded to wash them out; but in doing so observed that the holes were not filled with the red clay in which the boulder was found, but with sand. Mr. Manning shortly afterwards showed me this sand, and us I was aware that the bore holes of recent Saxicavæ frequently contained sand full of Microzoa, which fills the space once occupied by the flesh of the Mollusc, I suggested we should go to our mutual friend, Mr. J. D. Siddall of Chester, and examine it. We did so, and, on placing the sand beneath the microscope, were rewarded with the sight of several shells of the Foraminifer—Polystomella crispa. Mr. Manning thereupon remarked "if we are to succeed in finding Foraminifera in the boulder clay we must look for stones with holes in them." I, at the time, thought this very hopeless, as out of the thousands of boulders I had examined this was the first that I had seen with cavities in it.

After parting with my friends that evening, it occurred to me that the terminated shells of Purritella terebra would offer a still mere effective shelter to the Microzoa. These were very abundant in the boulder clay of Chester, and I possessed a great number of them.