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rapid changes of form and position which are observed in th spots themselves.

9. There are often seen, in the neighborhood of the spots, jets curved backward upon the solar disk in forms which are ser sibly parabolic.

10. The immense jets and erupted masses near the spots pand and vanish away more rapidly than in any other region.

11. On the area of the spots neither the photosphere nor the edge of the sun's disk shows any perceptible irregulat that is, neither any perceptible prominence nor depression.

From these results obtained by spectroscopic observations of the border of the sun and of the protuberances, Prof. Reshi is led to certain conclusions relative to the physical constn tion of the sun, among which the following may be mention

In the first place, the photosphere would appear to be the sur face of an incandescent liquid mass or stratum, of suitable specific gravity, by the weight of which various gases, and especially hydrogen, are confined and compressed in the interior of the sun, at an elevated temperature, under an enormous tension, and with a density differing but little from that of the superineumbent liquid stratum.†

These gaseous masses in the interior of the sun, not pet hav ing been brought to a condition of stable equilibrium, migos some portions be less condensed, and hence from hydrostatic pressure would rise toward the surface with great vel city, until, overcoming by their enormous expansive force i resistance of the liquid statum, they would burst through locity greater or less according to the depth from which they emerged, and the degree of tension in which they originally were, and would thus develop those jets or eruptions which constitute the protuberances.

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The masses thus erupted, then, would not be determined in their movement solely by their initial velocity and the action of gravitation, but would generally be subjected to ta operation of other forces which would con in their elevation, their diffusion, and their ramification into pose extraordinary forms which the protuberances present. rng to this h pothesis, the hydrogen issuing from the boy of the sun wo d serve as aliment to the chromosphere, repairing hus the raved losses of the latter, by its not improbable combination with the substances of the photosphere; and it does not appear to Prof Respighi absurd to suppose that this immensetum of meandescent hydrogen, that is, the chromosphere, y be the princi pal source of the heat radiated from the sun.

*See foot note on next page.

See the article of Prof. Zöllner, translated from the Proceedings of the Royal Saxon Society of Sciences, June 2, 1870, published Nov., 1870, in the Philosophi cal Magazine, where substantially these views are stated at length, and thoroughly discussed.

In regard to the spots, spectroscopic observations appear to show that they are neither cavities nor clouds, but are merely superficial modifications, that is, partial obscurations of the photosphere, produced probably, by scoria or scum floating upon it. On the contrary, regard being had to the well defined forms of the jets neighboring the spots, to their extraordinary subtilty, and to their enormous energy, the supposition does not appear to the author irrational, that the nuclei of the spots consist of portions slightly projecting from the photosphere, of solid asses or islands floating upon the liquid stratum which enlops the body of the sun. The immense chains of jets or protuberances, which rise ordinarily in the region of the spots, might be the cause of those great transformations which are observed in the latter, and determine, by their resistance in the superficial strata, currents in a direction opposite to that of the solar rotation, from which would result the proper motion of the spots themselves. The limits of an article forbid entering into the arguments by which Prof. Respighi endeavors to justify these conclusions, hypotheses, in great part at least, already advanced by others, but without that impress of plausibility and probability which they gain from the results of the spectroscopic observations discussed in this note.

The note is accompanied by four plates. Three of these represent 140 profiles of the sun, and the fourth contains sketches of some of the more remarkable protuberances observed by the author, and is the one accompanying this article.

On the plate, which contains 23 figures, the protuberances of approximately similar forms are grouped together. The observations were all made in 1870, and severally at the following times:

No. 1, Aug. 12, 11; 2, Feb. 26, 10h 40m; 3, Jan. 4, 1h 15m; 4, Oct. 7, 2h 50m; 5, Sept. 5, 1; 6, July 23, 10h; 7, Jan. 17, 3h 45m; 8, Nov. 12, 10h 20m; 9, Nov. 25, 9h 45m; 10, Jan. 24, 12h 40m; 11, Oc.. 25, 10h 40m; 12, Dec. 2, 1; 13, Aug. 26, 6h 15m; 14, Oct. 29, 1h 30m; 15, Oct. 2, 9h 45; 16, Nov. 24, 3h 48m; 17, March 11, 4h 40, 18, July 30, 9h 16m; 19, Aug. 24, 12h; 20, July 1, 2h 25m; 21, Oct. 28, 1h 24m; 22, April 18, 105 7; 23, Aug. 23, 10.

*This conclusion is entirely at variance with those of other observers, unless the author designedly omits the consideration of the penumbra, or makes no distinction between it and the umbra. The observations of Prof. Wilson in the last century, and of many others since, have shown that the nucleus or umbra is very often, if not generally, lower than the penumbra and the surrounding luminous masses. Some years since, Mr. De la Rue made a photograph of a solar spot, and another of the same spot after an interval of a day or two. When these were placed in a stereoscope the spot appeared funnel-shaped, the central portion being clearly lowAlso Zöllner and Lockyer have found in the displacement of the lines in the spectroscope, that there is sometimes decided evidence of a downward motion, in the dark portion of a spot. In the remarkable article, previously referred to, published in the Phil. Mag., Nov., 1870, Prof. Zöllner says. " almost all observers agree in admitting that the umbra lies at a lower level than the surrounding parts. The depth at which the umbra lies has been ascertained partly by direct (De la Rue, Stewart, Loewy), partly by indirect (Faye) observations, to be about 8'."

est.

A. W. W.

ART. XLIV.-Brief Contributions to Zoology from the Museum of Yale College. No. XIII.-Descriptions of new and imperfectly known Ascidians from New England; by A. E. VERRILL.

[Continued from page 212.]

Family, POLYCLINIDE.

Amouroucium glabrum Verrill, sp. nov. Figures 20 to 22. When young (fig. 20) this species forms small, clavate, or turbinate, translucent masses, attached by a narrow base, and containing only a few animals arranged somewhat irregularly around

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a single cloacal opening. The surface is smooth and glabrous, without adhering sand; the texture is rather firm, but so transparent as to distinctly show the animals, which are elongated and comparatively

large, standing nearly vertically, with the ovaries extending nearly to the base of the mass. The intestines, filled with pellets of focal matter, appear as conspicuous, dark, oblique spots.

Larger specimens (fig. 21) become 5 to 1 inch or more broad and have a large attachment and expanding sides, with a more or less irregular, smooth upper surface, which

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is usually slightly convex. Several cloacal openings are irregularly placed on the upper surface, and numerous individuals are irregularly scattered throughout the mass, though often forming rather indistinct circular groups around the apertures. The surface is glabrous and the tissues translucent, as in the younger specimens.

The animals, when mature, are mostly about 20 of an inch long, and about 05 in diameter: but many are 25 of an inch long and 06 to 07 in diameter. The thorax is longer and broader than the abdomen, and in specimens taken about the middle of August the cloacal chamber was distended by three to five large eggs, with the tadpole-shaped embryos nearly developed, while the post-abdomen was quite slender and the ovaries shrunken. Specimens obtained earlier (fig. 22) had the post-abdomen much thicker and filled with the large ovaries, in the upper part of which were eggs in various stages of growth, while the cloacal chamber

Figure 22.-Amouroucium glabrum Verrill, enlarged 10 diameters: a, anal orifice; b, branchial orifice; c, branchial sac; d, oesophagus; e, stomach: f, intestine containing focal pellets; g, anus; h, heart; o, ovary; p, eggs; 4, eggs containing embryos in process of development; s, testes; t, spermatic duct,-Original, by A. E. V.

contained but few eggs, in which the development was but little advanced. The post-abdomen is usually but little smaller at base than the abdomen, and tapers gradually to the obtuse end; its length is generally less than that of the thorax and abdomen taken together, but often exceeds it. The stomach (e, fig. 22) is short and broad, with numerous longitudinal, glandular ridges. The intestine is large, and usually contains from 7 to 10, large, blackish focal pellets.

The branchial orifice (b, fig. 22) is surrounded by six, small, tapering papillæ. The anal orifice is somewhat bilabiate, the lower lobe being stout and broad, the upper longer and tapering.

The color of the masses during life, is pale, translucent, bluish white; the branchia are light yellow; the stomach dark orange; ovaries yellowish white; the eggs containing embryos bright orange-yellow.

Eastport Harbor and Grand Menan, low-water under stones, to 60 fathoms, stony and shelly_bottoms, attached to stones, shells, ascidians, etc., common,-Exp. of 1861, '63, '64, '68, '70.

Amouroucium pallidum Verrill, sp. nov.

Masses sessile, hemispherical or subglobular, usually attached by a large base. Surface generally evenly rounded, sometimes irregular in large specimens, smoothish, but thinly covered with minute, firmly adherent particles of fine sand, which are imbedded in the surface of the common tissue and scattered throughout its substance. The texture is softer and more gelatinous than in the preceding species. The cloacal openings are few in number and irregularly placed, except in small specimens, which usually have but one large central opening. The animals are much smaller and more numerous than in the preceding species, often forming somewhat circular groups of six or eight individuals around the cloacal openings; outside of the circular groups they are usually irregularly scattered, but sometimes form linear series of eight or ten, and in young specimens with but one central opening they often form a larger outer cir cle, which is near the margin, more or less irregular, and composed of numerous individuals. Except in their much smaller size, the animals resemble those of the preceding species, though they are perhaps a little shorter and thicker in proportion. The post-abdomen, in all the numerous examples examined, was small, thick, obtuse, and decidedly shorter than the abdomen and thorax taken together; it contains few ovules in two series, and often terminates in two slender papillæ.

The larger specimens of this species are 50 to 75 of an inch in diameter; the largest animals are 08 to 11 long, by 03 to 04 of an inch in diameter, but many are much smaller than this; the largest one examined was 15 long by '05 of an inch in diameter.

The color of the masses, in life, is pale, translucent, grayish or bluish white, with yellowish white animals.

Eastport and Grand Menan, with the last,-Expeditions of 1868 and '70.

Amouroucium pellucidum Verrill.

Alcyonidium? pellucidum Leidy, Journal Phil. Acad. Nat. Sciences, 2nd ser., vol. iii, p. 142, Pl. x, fig. 25, 1855.

"Polypidom translucent white, attached by narrow fasciculated bases, which are extended in a procumbent manner and then expand into wedge-shaped masses, upon the free, flat surfaces of which the polyps are clustered. Polyps with bright orange colored tentacula.

Attached to rocks, mytili, sponges, etc., at Point Judith (R. I.); abundant.

The masses of A. pellucidum from the white, fasciculated points of attachment to the broad free surfaces are up to an inch in thickness. Although I preserved a number of specimens in fresh sea-water for some days, I could not induce the polyps, if they were such, to protrude from their cells, and I only had the opportunity of examining them in their retracted condition as represented in figure 24, plate x."

The figure referred to very well represents the thorax and abdomen of a species of Amouroucium, allied to A. glabrum V., except that the longitudinal ribs of the stomach were mistaken for the retracted tentacles of a Bryozoan, and figured as such. The post-abdomen is not shown, and was undoubtedly accidentally broken off in dissecting it out.

The cloacal cavity, or atrium, is represented as distended by four large eggs, containing well advanced embryos; the branchial sac has a broad dorsal and 12 transverse ducts; the intestine is like that of A. glabrum, and contained dark focal pellets; the branchial opening has six rounded papillæ; the anal has an elongated lobe above it.

Two specimens, dredged at Wood's Hole, Mass. by Prof. H. E. Webster, appear to be identical with this species. These form low, soft, broadly expanded and flat topped masses, up to 2 inches in diameter, and 50 to 75 thick, attached by the middle of the lower surface and proliferous around the edge of the base, which is surrounded by young colonies, composed of but few individuals arranged around a central orifice and covered externally with adhering sand. These young colonies are elongated, expanding to the truncate upper end, and ascend very obliquely, the outer ones remaining free, except at base, the inner ones coalescing more or less completely with the central mass. The common tissue of the upper side is very soft, gelatinous, translucent, with but little adhering sand; the sand increases toward the margin, and on the outer and lower sides

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