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different from previous descriptions and figures, looked upon it as a new species, and named it C. mirabilis.” Adult specimens have since been found by M. Gervais, and I have met with them in abundance in Ireland, and in other parts of the British Isles. A more interesting and beautiful animal than a fully developed specimen of Cristatella mucedo can scarcely be imagined. The entire colony is of an oval shape, convex above and flat below, where it attaches itself to neighbouring objects. Upon the convex surface are arranged the orifices through which the polypides emerge, they are placed near the margin, and run round the entire coenoecium in three regular concentric series, which alternate with one another, and leave an oval space in the centre where no orifices exist. In the middle of the flattened under surface is an oval disc, resembling the foot of a gasteropodous mollusc ; on this disc, which is contractile, and admits of frequent change of shape, the colony adheres to neighbouring objects, or creeps about on the submerged leaves and stems of aquatic plants. From the edges of the disc a flat space extends outwards, passing beyond the external series of orifices in the form of a projecting margin, whose interior is occupied by a series of tubular cells or chambers, visible through the translucent skin, and extending in a radiating direction from the disc outwards, but possessing no external opening. The tentacula are about eighty in number, being more numerous than in any other known Polyzoon, except, perhaps, Pectinatella, Leidy. The coenoecium is of a dull yellow, or sienna colour. The polypide is nearly of the same colour, with the exception of the intestine, which, in well-fed, healthy specimens, is light bluish-green. The largest specimens measure about two inches in length and a quarter of an inch in breadth, and, with the polypides extended, are, at the first glance, not unlike certain hairy caterpillars, or, as M. Gervais has aptly enough suggested, the silk fabric known by the name of Chenille. Such large specimens are very sluggish, and change their place with reluctance, at least when kept in confinement; but specimens of about half an inch in length creep about on the sides of the jar in which they are preserved at the rate of several inches in the day; they generally prefer keeping near the surface of the water, and seem to be much under the influence of light; indeed, while the greater number of the fresh-water Polyzoa lurk on the under surface of stones and in dark recesses, Cristatella loves to expose itself to the full light and warmth of the sun. It differs, moreover, from all the Polyzoa with whose habits I am acquainted, in the constant pleasure it takes in maintaining its polypides in the exserted state; these, indeed, must be very roughly handled to cause them to withdraw into their cells; and the annoyance is no sooner removed than they again emerge. This exquisite little Polyzoon seems, in fact, capable of existing only under the full influence of light, and in the midst of the innumerable vortices excited in the surrounding water by the vibratile cilia of its tentacles. The statoblasts are very characteristic. They are about 3, of an inch in diameter, exclusive of the marginal spines, and, with the exception of the statoblasts of Pectinatella, which they closely resemble, are larger than those of any other fresh-water Polyzoon. They are also, with the same exception, the only ones having an orbicular shape. One face is a little more convex than the other. The annulus is wide, very distinctly cellular, and of a light yellow colour. The disc is deep reddish-brown, and elegantly mamillated. The spines

* “Report of Meeting of British Association, held at Edinburgh, 1834.’

spring from both faces of the disc, just within the annulus, and thence radiate outwards, extending for some distance beyond the margin. The spines springing from the more convex face are somewhat longer and more numerous than the others, and alternate with them. All the spines are terminated by two, three, or four curved hooks resembling grappling-irons. Towards the end of summer, the statoblasts occur in considerable numbers in the interior of full-grown specimens, and are visible through the transparent tissues of the animal. On the death and decay of the coenoecium they are liberated, when they become attached, by means of their hooked spines, to various aquatic plants, and ultimately open for the escape of the young, by the separation of the two faces, at the commencement of the following summer. The young, on its escape from the statoblast, is at first solitary, but is rapidly multiplied by the pro

duction of gemmae. I have never met with Cristatella later than the autumn; it seems to be strictly annual in

its duration.

Genus II. PECTINATELLA, Leidy, 1851.

Name.—A diminutive noun, formed from pecten, a comb, in allusion to the form of its tentacular crown.

In the ‘Proceedings of the Academy of Natural Sciences of Philadelphia' for September, 1851, a new fresh-water Polyzoon is described by Dr. Joseph Leidy, under the name of Cristatella magnifica. The statoblasts of this animal resemble those of Cristatella mucedo, and it was this character which induced Leidy to refer his new Polyzoon to the genus Cristatella. It is not, however, furnished with a disc fitted for locomotion, and it has the orifices scattered irregularly over the surface, characters which bring it very near to Lophopus, but which at once exclude it from the genus to which Leidy had referred it. Of the untenableness of this association the author became almost immediately aware, and, in the next number of the ‘Proceedings, he instituted for it a new genus, with the following diagnosis:

Generic character—“Coenoecium massive, gelatinoid, hyaline, fixed, investing bodies; orifices arranged in irregular lobate areolae upon the free surface. Lophophore crescentic. Ova (statoblasts) lenticular, with an annulus and marginal spines.” Leidy.

Species unica. Pectinatella magnifica, Leidy. Specific character.—Same as that of the genus.

SyNoNYMs.—1851. Cristatella magnifica. Leidy, Proc. Acad. Nat. Sci. of Philadelphia, Sept., 1851.

1851. Pectinatella magnifica. Leidy, Proc. Acad. Nat. Sci. of Philadelphia, Nov., 1851.

Iconography.—No published figure.

HABITAT.-“Ditches and sluggish streams; found only in shady situations; always incrusting dead branches of trees.” Leidy.

Localities.—“About Philadelphia.” Leidy.

It is greatly to be regretted that we have no published figure of this beautiful Polyzoon, which must well deserve the name by which the species is designated. Dr. Leidy gives us the following more detailed description of it: “Polypidom massive, incrusting bodies, from a few inches to several feet in length, by a few lines to two inches in diameter; gelatinoid, consistent, hyaline, with numerous polypiupon the free surface arranged in close irregular areolae. Polypi furnished with two lobes, conjoined together in the form of U, enclosing the mouth at the base, and having, diverging from the margin, from 50 to 80 sigmoid tentacula arranged at the summit in the double outline of U, with the extremities of the arms of the latter inclining towards each other; lip elevated, with the base of the tentacular lobes and the lower-fourth of the inner margin of the tentacula in the vicinity of the mouth, lake or dark rose-red colour; qosophagus colourless; stomach longitudinally folded, yellowish-brown; rectum dilatable, hyaline, its extremity slightly projecting, but retractile; length from the bottom of the stomach to the top of the extended tentacula, 13 line; long diameter of tentacular expanse, to 3 of a line; length of tentacula, 's of an inch; breadth, room of an inch. “Ovum (statoblast) lenticular, brown, enclosed at the margin by a brownish-white annular cellular sheath, on of an inch deep upon one side, low of an inch on the other, furnished at its outer edge with 14 to 16 appendages, on inch long, terminating in a double, rarely a triple, hooklet. Ovum (statoblast), with its sheath, thin, discoidal, bent, so inch broad, with its appendages enveloped in a hyaline, albuminoid mass; when ripe, floating. “The surface of the polype mass has the appearance of being covered with a dense mucor from the numerous tentacula projecting from it. Immediately beneath this, is a layer having a faint roseate hue, from the red colouring in the vicinity of the mouth of the polypi; then succeeds a layer of a dirty-yellowish colour, arising from the stomachs of the animals; beneath which are numerous opaque, white, yellowish, and brown spots, which are ova in various stages of development; and, finally, the greater depth of the mass consists of a perfectly hyaline, consistent, gelatinoid substance. “The animal is not so irritable as Plumatella, but is, like it, capable of entirely retracting within its tube, in which state the stomach appears transversely wrinkled. “The ova, as they are detached from the mass, rise nearer to the surface of the water, and float.” The luxuriance of growth of Pectinatella magnifica in the only locality which has as yet been recorded for it, is especially worthy of attention. It would seem, indeed, that the masses formed by it attain to a size which surpasses that of any other species. It is certainly one of the noblest of the fresh-water Polyzoa; and it is much to be hoped that its discoverer will not long delay in giving us a figure, with anatomical details, of so beautiful and interesting an animal.

Genus III. LophopUs, Dumortier, 1835.

Name.—From Aópos, a crest, and Toys, a foot.

In a historical point of view, Lophopus is the most interesting genus of the entire class. The “Polype à Panache,” discovered by Trembley, in 1741, was the first Polyzoon of which we have any record. It long continued to be confounded with species of Plumatella and Alcyonella, until Dumortier, rediscovering it in 1834, and perceiving its distinctness, assumed it as the type of a new genus, and described it under the name of Lophopus crystallinus. Though the characters given by Dumortier to his new genus are not entirely correct, yet with some alterations in his diagnosis, Lophopus must be preserved as a well-marked and easily characterised generic form.

Shortly after the original discovery of the “Polype à Panache,” the same animal was met with in England by Baker, who described it under the appellation of the “Bellflower animal.” M. Van Beneden believes Baker's animal to be distinct from that of Trembley, and describes it by the name of Lophopus Bakeri; but there are certainly no grounds for this distinction. Indeed, I am convinced that the animal called L. Bakeri by Van Beneden, and which has been so beautifully figured by this naturalist, is entirely identical with L. crystallinus; I must therefore still consider the genus as consisting of but a single species, the original “Polype a Panache” of Trembley.

Generic character.—Coenoecium sacciform, hyaline, with a disc which serves for attachment but not for locomotion; ectocyst gelatinoid; orifices scattered. Statoblasts elliptical, with an annulus, but without marginal spines.

Species unica. Lophopus crystallinus, Pallas. Pl. II.
Specific character.—Same as that of the genus.

SYNoNYMs.—1744. Polype à Panache. Trembley, Mém. sur les Pol. d’eau douce, p. 210, tab. 10, figs. 8, 9. (Original figures.) 1746. Polype à Panache. Baeck, Acta Suecica, p. 198, tab. 6, figs. 3, 4. (Figures copied from Trembley.) 1753. Bell-flower Animal. Baker, Employment for the Microscope, p. 306, pl. 12, figs. 15-22. (Original figures.) 1766. Tubularia crystallina. Pallas, Elenchus Zooph., p. 88. 1767. Tubularia campanulata. Linnaeus, Syst. Nat., edit. xii. 1789. Tubularia reptans. Linn., Syst. Nat, cura Gmelin, p. 3835. 1789. Campanulated Tubularia. Shaw, Nat. Miscel, tab. 854. (Original figure.) 1806. Tubularia campanulata. Turton, Linn., Syst. Nat., vol. iv, p. 668. 1816. Plumatella cristata. Lamarck, Hist. des An. sans Vert., 1st edit., vol. ii, p. 107.

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