of the animal were completed, the young Lagotia had increased in size, and its tube had become more opaque.

The spiral structure of the tube appears to afford a provision for its growth similar to that found in the articulated shell of the Echinus. In Lagotia producta, increase in length of the tube would be effected by the deposition of chitine on both edges of the spiral ribbon, while increase in its calibre would take place by the gradual unrolling of the same. The chitine is probably secreted by the thick inner coat of the tube; while the external coat appears to act, like the "colletoderm " of zoophytes, as a cement for attaching the cell to the rocks. These young Protozoa frequently assembled in clusters, and secreted a quantity of "colletoderm," which glued all their cells into a single mass.

So far, the observation as to the reproduction of Lagotia is in some measure satisfactory; but it still remains to be discovered how the ciliated larvæ are produced. In Epistylis nutans, one of the Vorticellina to which Lagotia is allied, an encysting process takes place, according to Stein, by which the animal takes the form of an Acineta. The ciliated head is absorbed; the body is inclosed in a tough tunic; and numerous long capitate tentacles are put forth, which have the property of sucking tubes, and quickly absorb the fluid contents of any animalcule coming in contact with them. Within this Acineta body one or more ciliated embryos are formed, and successively given off, until the substance of the Acinetal is entirely exhausted, and it becomes an empty sac. A similar transformation into the Acineta state has been noticed in Vaginicola, a still nearer ally of Lagotia. I have, however, not been able to detect any such change in the subject of this notice.

2. Zooteirea religata. (Fig. 7.)

This Protozoan is an inhabitant of deep water, and was dredged from the oyster-beds opposite to Newhaven. It was attached in considerable numbers to the concavity of the lower valve of an old oyster-shell, from whence it propagated itself to the sea-weeds of the vessel in which it was confined. Zooteirea may be briefly described as an Actinophrys mounted

ec

on a contractile stalk. Actinophrys, again, consists of a globular mass of sarcode, in which may be distinguished two tissues an internal one, which I shall call "endosarc," enveloped by an external tissue, "ectosarc." The endosarc is dense, loaded with molecular matter and nutritive granules; the ectosarc transparent, and produced into tentacular appendages. Actinophrys has no mouth. Animalcules, seized by the tentacles, are drawn to the surface of the body, the soft sarcode of which becomes depressed, closes over them, and envelops them. They sink into the endosarc, and are absorbed. The endosarc is the alimentary tissue; probably also the reproductive tissue. The ectosarc exercises the prehensile function. The tentacular processes of Actinophrys are homologous with those prehensile processes of the " toderm " which I have described as existing in several classes of aquatic animals, and to which I have given the term "palpocils," a term which has lately been adopted by my friend Mr Gosse, in his interesting paper on Sarcodyction catenata. In Zooteirea, when expanded, the whole of the ectosarc is prolonged into long and exceedingly attenuated palpocils, until the animal assumes the appearance of a globular brush of spun glass mounted on a transparent stalk. When irritated, the animal slowly contracts its stalk until the body is brought close to the surface on which it is attached, and the palpocils are contracted to a mass of little nodules (fig. 7, b). The stalk is homogeneous, and is, as are the palpocils, a process of the ectosarc. A group of these animals form a very striking microscopic object when seen by the dark field illumination,—two cones or brushes of light appearing to issue from opposite sides of the body of each, and to pass round it in opposite directions when the mirror is moved. I have derived the name Zooteirea from Zwoo and rigsoo, a star, or rather a constellation.

3. Corethria Sertulariæ. (Figs. 8, 9, and 10.)

This remarkable animal has occurred plentifully during the last few summers on the Sertularia pumila, which grows at low-water mark near Granton. I have only found it in one locality, at the extremity of the first ridge of rocks which runs out into the sea west of the long breakwater. Although

3d,

its anatomical structure is protozoan, it can be classed in no described family of Protozoa. It consists of three parts: 1st, An oblong cushion of opaque granular sarcode (fig. 8, a) attached to the corallum of the zoophyte, and sometimes containing a few vesicules. 2d, A long column attached to the cushion (b), bearing a brush of short tentacles. This column consists of two tissues; an outer coat thrown into numerous transverse folds or wrinkles (fig. 9, a), and an inner core displaying a faintly-marked longitudinal structure (b). At the top of the column this inner coat appears to terminate in a brush, or rather mop of from ten to more than forty tentacles (c), which have occasionally a slow and rather irregular waving motion, though they are generally at rest. There exists, but not invariably, a long, spindle-shaped, and rather curved process of a granular tissue, similar to that of the cushion (fig. 8, c), also attached by one extremity to the upper surface of that body, and having at its unattached extremity a clear space, which opens externally by a small oral aperture. This body is often absent, and I have seen it attached alone to the Sertularia. I am therefore inclined to consider it either a gemma or a parasite belonging to Gregarinæ. Although Corethria bears no resemblance in form to any known. Protozoan, it has anatomically all the elemental tissues of an Actinophrys. Let us suppose an Actinophrys in which the ectosarc or prehensile tissue is segregated from the endosarc or nutritive tissue, the former, instead of forming a multitude of palpocils, being gathered together into a single large tentacle, surrounded in greater part by a wrinkled cuticle, and undergoing division at its summit into a number of palpocils. Such a structure I have observed in the compound palpocils situated on the tentacles, at the extremities of the rays of Solaster papposa, and such appears to be the structure of the "mop" of Corethria. Food taken by the palpocils would be transferred through the soft sarcode composing the centre of the pillar, and digested by the granular endosare of the cushion below. I have seen the spores of Algae thus absorbed into and pass through the tentacles of Ephelota apiculosa. A like observation has been recorded with regard to the tentacles of an Acineta. From xógn@gov, a mop.

4. On Salpistes (Stentor) Mülleri and castaneus. (Fig. 11.)

In the last edition of Pritchard's "Infusorial Animalcules" it is stated that Stentor Mülleri, "when kept long in glass vessels, fasten themselves to the sides, form a slimy covering around them, and die ;" and, further, that Ehrenberg had remarked that "they would gradually congregate, select some particular spot, and then attach themselves, evincing, as it were, not only a degree of sociality, but a mental activity." In their apprehension of these facts I believe the authors above quoted to be mistaken. It is well known that many aquatic animals have the power of secreting masses of viscid gelatinous matter, which does not readily undergo decomposition, to serve as a nidus for the protection of their ova. Thus the nudibranchiate and other molluscs deposit on stones and weeds long convoluted ribbons of clear firm jelly filled with their eggs, which remain therein until hatched. Many insects, aquatic in their earlier stages of existence, adopt the same mode of protecting their young. In the genera Sertularia, Plumularia, Campanularia, and Laomedea, species also are found in which the young undergo partial development whilst still contained in gelatinous cases attached to the exterior of the reproductive cells, as I have already described to the Society in the case of Laomedea lacerata. Other animals employ the same matter to form envelopes or lorica, into which they can retire protected from harm. In this way is formed the "house" of Appendicularia flabellum, of which Mertens has given so marvellous an account, mistaking it for a respiratory organ. Amongst the Rotiferæ we find Stephanoceros, Floscularia, Limnias, Melicerta, and others, each living privately in its solitary abode, formed either of clear gelatine, or of the same substance strengthened with mud or other extraneous matters; while in the genus Conchilos a colony of animals unite their efforts to form a transparent globe, which is rapidly rolled through the water by a multitude of living wheels. Descending to the Protozoa, we may see Ophrydium versatile, an animal scarcely visible to the unassisted eye, attaching itself to our tanks by its little speck of

jelly. It then immediately proceeds to multiply itself in geometrical proportion by fissure until masses are formed, which, under favourable circumstances, attain a diameter of three or four inches, and consist of aggregations of many thousands of zooids. In this Protozoan the division is not complete; the zooids are united by fine threads, which permeate the gelatinous mass, and are homologous with the stalks of Epistylis. These threads also appear to have the property of transmitting nervous impressions through the whole mass of this compound animal, and rendering the movements of the associated zooids consentaneous.

When in England some years ago, I found in one of my fresh-water aquariums a great number of specimens of Stentor Mülleri, each one of which was surrounded at its base by a flocculent deposit similar in structure to the lorica of Ophrydium versatile, and into which the animal could withdraw itself. At first I considered that this state was the result of disease, but further experience showed that the deposit was never absent. Many of the animals inhabited a tall gelatinous pillar, by which they raised themselves considerably above the surface on which they grew (fig. 11). Others by fissure had formed colonies, which were attached to the glass, or hung downwards while floating on the surface of the water; others, again, were swimming naked in search of sites for future erections; but no fixed animals were found to be destitute of a lorica. I have repeatedly met with this animal since, and always in the same loricated state.

In the summer of 1857, a small species of Stentor, of a deep chestnut colour, occurred in the pond of the Edinburgh Botanical Gardens, which is in the habit of secreting a lorica like that of Stentor Mülleri. This species, which I have called castaneus, selects the tips of the shoots of Myriophyllum for its abode, and glues all the opening leaflets together with a mass of jelly, from which the zooids protrude their wheel-bearing heads. The possession of a lorica removes. Stentores Mülleri and castaneus from the family Vorticellina to that of Ophrydina, which (says Ehrenberg) "includes true Vorticella or Stentors inclosed in a gelatinous membranous little box" or shell. In the last family, a new genus will

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