addition to the length of the spiral ribbon, and that with the increasing age of the animal the number of spiral turns would continually increase. Such, however, is not the case, as I shall proceed to show.

Mode of Reproduction in Lagotia.

As I was anxious to ascertain the mode of reproduction in Lagotia, I was kindly allowed to take away with me several of the stones from the aquarium. These were placed in a large glass vessel of sea-water, and careful daily search was made for some weeks to discover larvæ, but without success, although young Lagotias were beginning to attach themselves to the sides of the glass. At last, I discovered several dark green specks swimming in the water: these were caught one by one, placed in large flat cells, and covered by bell-glasses, to prevent evaporation, where they became developed into Lagotias.

The young of Lagotia producta, in its earliest stage (fig. 4), is a short cylindrical body, with rounded extremities of a dark sea-green colour. The surface of the body is marked by coarse striæ, each of which carries a fringe of long lashing cilia, by the aid of which the animal urges itself rapidly through the water, at the same time rotating on its axis. It quickly assumes a more lengthened form (fig. 5), the anterior extremity of the cylinder puts forth a fringe of long cilia, and the posterior extremity becomes pointed, while the cilia of the body become much diminished in size. A number of young at this stage were placed in the flat cells, and were found the next morning to have attached themselves to the surface of the water as to a solid substance, and to have developed their tubes with all the spiral rings complete, the imbrication of the rings being even more marked than in the adult specimens. The rudiments of the bilobed rotatory organ had also appeared (fig. 6); while the cilia of the body had still further decreased in size, although the striated texture of the surface was still strongly marked, and formed a beautiful object under strong microscopic power. In three or four days, the lobes of the rotatory organ and the general structure

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 Acineta 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

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 "ectoderm " 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 con-
taining 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 dis-
playing 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 ex-
tremity a clear space, which opens externally by a small oral
aperture. This body is often absent, and I have seen it at-
tached alone to the Sertularia. I am therefore inclined to con-
sider 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 endosarc 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 ten-
tacles of an Acineta. From xógnégov, 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