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Specific character.-Conocium adherent, creeping, irregularly branched, branches composed of a series of large conical cells, tapering towards the orifice, destitute of furrow; the upper portion of the cell almost colourless and freckled with minute, opaque, white spots. Tentacula about sixty; calyx distinctly festooned. Statoblasts broad.

SYNONYM.-Plumatella punctata. Hancock, Ann. Nat. Hist., 2d series, vol. v, p. 200, pl. v, figs. 6, 7, and pl. iii, fig. 1.

Iconography.-Original figures of Hancock.

HABITAT.-Adhering to the under side of stones in lakes.

LOCALITY.-Bromley and Crag Loughs, Northumberland. Hancock.

The following is Mr. Hancock's description of this species:

"Polypidom adhering throughout, coriaceous, pellucid, of a pale, watery, green colour, irregularly but not much branched, seldom extending more than half an inch; branches composed of a series of large, conical cells, tapering upwards towards the aperture, sometimes considerably and rather suddenly dilated at the base, resembling in form some of the Ascidians; the upper portion of the cell almost colourless, and freckled with minute, opaque, white spots, most crowded towards the orifice. Tentacles white, not more than sixty in number; membrane at their origin rather wide, scalloped, the points of the scallop extending for some distance up the back of the tentacles in the form of broadish laminæ arched outwards. Esophagus and stomach appearing through the transparent walls of the cell of a pale yellow colour. Egg perfectly black, large, broad, and oval.

"Upwards of a dozen specimens of this fine species occurred in Bromley Lough, adhering to the under side of stones; it was likewise taken in Crag Lough. None of the individuals much exceeded in size that represented in the figure, nor did they vary in any remarkable manner either in form or colour. It is not, however, without hesitation that I ventured to characterise this as a new species, as Professor Allman informs me that it may perhaps turn out to be P. repens; but that form is stated to be large and of luxuriant growth, and to have the polypidom tubular with the cells dilated at the orifice-characters which do not at all agree with P. punctata. Indeed it can scarcely be considered a true

Plumatella."

I have never seen a specimen of P. punctata, but having read Mr. Hancock's detailed description I now agree with him in considering the species as a good one. Still, however, it comes very near to P. repens, closely resembling the young state of this species before the conocium has acquired the more decidedly tubular condition of the adult.

4. Plumatella vesicularis, Leidy.

Specific character." Conocium radiating and branched, attached, colourless, and transparent; each segment slightly dilated and much broader than the protuberant orifice of exit.

Length of the segments about 1 mm., breadth 1 mm. Animal colourless. blasts) oval, lenticular, with an annulus, but without spines." Leidy.

Ova (stato

SYNONYM.-1854. Plumatella vesicularis. Leidy, Proc. Acad. Nat. Sci. of Philadelphia, vol. vii, p. 192.

Iconography.-No published figure.

HABITAT.-On the under side of flat stones in running water.

LOCALITY.-Schuylkill River, Philadelphia. Dr. Leidy.

"This species of Plumatella is as limpid as the water in which it lives; rows of colourless vesicles with a whitish line passing through their axis. observed with rows of imbricated blackish eggs instead of the latter line. from a quarter of an inch to two inches square." Leidy.

and it resembles Frequently it is Patches are found

All we know of the present species is from the above short description by Dr. Leidy. It seems to approach closely to Plumatella punctata, Hancock; and the absence of an authentic figure is here again much to be regretted.

5. Plumatella fruticosa, Allman. Pl. VI, figs. 3-5.

Specific character.-Conocium irregularly branched, attached only at its origin; cells cylindrical, destitute of furrow, but obscurely keeled. Statoblasts elongated.

SYNONYMS.-1844. Plumatella fruticosa. 1846. Plumatella fruticosa. 1847. Plumatella fruticosa.

Iconography.-No published figures.

Allman, Ann. Nat. Hist., vol. xii, p. 330.
Allman, Proc. Roy. Irish Acad., 1846.
Johnston, Brit. Zoophytes, 2d edit., p. 404.

HABITAT.-In lakes and ponds, and in rivers where the current is not too rapid, attached to the under and shady side of stones and to the stems and under side of the leaves of aquatic plants. Loving the shade.

LOCALITIES.-British: In the Regent Canal, London; the Chelmer Canal, Essex; Grand Canal, near Dublin; River Bandon; a small lake near Glandore; and in some other lakes and ponds in the county of Cork. G. J. A.

Foreign Lake of Lucerne, and Lake Seculejo in the Pyrenees. G. J. A.

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This species delights in still and slowly-running water, where it may be seen in the form of elegant little tree-like growths attached to stones and the stems of Potomogeton, Myriophyllum, and various other aquatic plants. It is easily distinguished from all the other species of Plumatella, except the free variation of P. repens, by its irregularly branched, bushy, non-adherent

mode of growth and from the latter it is at once known by its cylindrical branches and narrow statoblasts. In its general habit it bears a very close resemblance to Fredericella, indeed from a luxuriant specimen of the latter polyzoon it is frequently impossible to distinguish it without an inspection of the polypides or statoblasts.

I have found this species throughout the entire summer and autumn.

6. Plumatella coralloides, Allman. Pl. VII, figs. 1—4.

Specific character.-Conocium attached only at its origin, and forming dense, erect tufts of dichotomously branched tubes, destitute of furrow and keel. Tentacula about sixty. Statoblasts broad.

SYNONYM.-1850. Plumatella coralloides.

Iconography.-No published figure.

Allman, Brit. Assoc. Report, 1850.

HABITAT.-Attached to submerged bodies in still water. Avoiding the light.

LOCALITY.-The "London Docks" on the River Thames. Mr. Bowerbank and G. J. A.

This species rises to the height of from half an inch to an inch, in the form of dense tufts, consisting of tubes which repeatedly branch in a dichotomous manner as they extend upwards from the base. The branches are approximated, and are formed of a series of pellucid tubular cells, which are for the most part dilated upwards, and thus present a sort of claviform figure, while the ultimate ramuli, varying in length, bring all the orifices to the same level, and give to each tuft somewhat the appearance of certain varieties of that form of inflorescence known to botanists by the name of cyme. Almost every cell is separated from its neighbour by a very complete transverse septum. This septum is of a dark reddishbrown colour; and being visible through the pellucid walls of the cell, gives to the tubes. the appearance of being divided at regular intervals into distinct joints. The cells are light yellowish-brown, of a membrano-corneous texture, and nearly free from earthy deposit.

P. coralloides presents in habit a very close resemblance to Alcyonella fungosa; indeed, it must be viewed as possessing an intimate relation with the latter Polyzoon; the already approximated branches need but advance one step further in their approximation, and by adhering to one another, give rise to a genuine Alcyonella, scarcely distinguishable from A. fungosa.

The present species occurred rather abundantly in the London Docks, on the River Thames; where, in company with Mr. Bowerbank, I met with it in July, 1849, attached to floating logs of wood, together with P. repens and Cordylophora lacustris, and generally immersed in masses of Spongilla fluviatilis.

7. Plumatella emarginata, Allman. Pl. VII, figs. 5-10.

Specific character.-Cœnæcium adherent, creeping; cells cylindrical, with a very distinct furrow, which gives an emarginate appearance to the orifices, and becomes continuous below, with a prominent keel. Tentacula about forty. (Free). Statoblasts elongated.

SYNONYMS.-1804. Tubularia repens? Vaucher, Bull. de la Soc. Philom., ann. xii, No. 81,

pl. 19, figs. 1, 2, 3, 9, 10.

1816. Plumatella repens? Lamarck, An. sans Vert., 1st edit., vol. ii, p. 108.
1824. Naisa repens? Deslongchamps, Encyc. Méth., Zooph., p. 561.

1836. Plumatella repens? Lamarck, An. sans Vert., 2d edit., vol. ii, p. 123.

1844. Plumatella emarginata.

1847. Plumatella emarginata.

Allman, Ann. Nat. Hist., vol. xii, p. 330.
Johnston, Brit. Zooph., 2d edit., p. 404.

Iconography. Possibly Vaucher's figures of his Tubularia repens; otherwise no published

figure.

HABITAT. In streams and rivulets, adhering to the under side of stones.

LOCALITIES.-British: In a beautiful little rivulet near Bandon, County of Cork. In the River Dodder, near Dublin, abundant. In a rivulet near Arklow, in the County of Wicklow, and in localities furnishing a similar habitat in other parts of Ireland. G. J. A. Foreign: Lago di Como. G. J. A.-France? Vaucher.

The well-marked furrow in this species, commencing near the orifice in a transparent, triangular space, looking as if a piece had been cut out of the margin of the orifice, suggested the specific name, as this Polyzoon was, at the time of its discovery, the only species known with a similar condition of the ectocyst. Subsequent search, however, has brought to light several others with the same character; and though the name has thus lost its exclusive appropriateness, it has been nevertheless deemed convenient to retain it.

This Polyzoon is more opaque and coriaceous than P. repens. The ectocyst, except in the immediate vicinity of the orifices, and at the commencement of the furrow, is loaded with minute, irregularly angular, siliceous particles, giving it under the microscope the appearance of being in a great measure composed of agglutinated sand. It is of a ferruginous. colour, becoming lighter towards the orifices, while the uniform diameter of the branches deprives it of the peculiar concatenated disposition which is generally, so striking in P. repens. It is irregularly branched, adhering closely to the surface on which it grows, but frequently sending off several short free branches of about half an inch in length.

P. emarginata, unlike most of the other fresh-water Polyzoa, delights in rapid rivulets, though it also flourishes luxuriantly in the more quiet waters of lakes. It is eminently lightshunning; for though it loves the purest and clearest waters, it is always found on the under surface of stones, where scarcely a ray of even repeatedly reflected light can reach it. It occurs in greatest perfection during the summer and autumn; at the latter period the

tubes are loaded with elongated ova, which lie quite loose within them, and are liberated on their rupture; besides these bodies, we find here also, as in Alcyonella Benedeni, ova of a broadly elliptical shape and imperfectly developed annulus; these last are always attached firmly to the walls of the tube. P. emarginata admits of an interesting comparison with Alcyonella Benedeni, to which it seems to be related exactly as P. repens is with A. fungosa.

8. Plumatella diffusa, Leidy.

Specific character.-Conocium adherent, creeping; cells "keg-shaped" towards the orifices, which are rendered emarginate by a notch-like furrow continued down one side of the cell on a slight keel. Tentacula forty-two. Statoblasts elongated.

SYNONYM.-1851. Plumatella diffusa. Leidy, Proc. Acad. Nat. Sci. of Philadelphia, vol. v, p. 261.

Iconography.-No published figure.

HABITAT. In running water, covering the under surface of submerged stones, and extending over spaces of from one to several square feet.

LOCALITIES.-Schuylkill and Delaware Rivers, Pennsylvania, and the brooks flowing into them. Dr. Leidy.

Dr. Leidy gives the following more detailed description of this species:

"Polypidom diverging from a centre over large surfaces, consisting of a series of simple curved branches, from one to two lines long, rising from one another upon the convex side, and attached throughout their length, except at the extremities, from to of a line, which are erect, keg-shaped, or a little dilated at the middle, and contracted at the orifices. Border of the orifices deeply emarginate, and continuous with a fissure down the inner or concave side of the branches upon the summit of a slight ridge. Colour dirty olivaceous brown, with the erect extremities of the branches yellowish or translucent whitish.

"Polypi with forty-two divergent sigmoid tentacula arranged at the summit in the outline of a reniform disc. Length of the tentacula about of a line; colour of stomach greenish-yellow.

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"Ovum (statoblast) with its marginal sheath, semi-oval, of an inch long, of an inch broad. Sheath whitish, translucent, smooth, cellular; with the aperture on its convex side of an inch in diameter; that upon its flat side of an inch. Ovum (statoblast) lenticular, reddish-brown."

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Plumatella diffusa comes certainly very close to P. emarginata, the slight dilatation of the cell just below the orifice being the only point in which I can find any valid distinction between the two species.

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