ach, how do the embryos hatching from those eggs reach a suitable place for their development into hydatids, which place is, in the sheep, the brain? It had been erroneously assumed that they bored with their spines recta via from the stomach through all the tissues and organs until they reached the brain. Accordingly, in the hog, the embryos of the Tænia would have to go from the stomach into the muscles; in the rat, into the liver; and in the ox, into the lungs; for it is only in these particular organs that these hydatids are found.

R. Leuckart, however, discovered the way in which the embryos actually reach their destined resting places. On feeding rabbits with the eggs of Tania serrata, he found that, some hours after the feeding, the eggshells were already dissolved into prismatic granules by the juices of the stomach, and the embryos set free. But on putting the eggs immediately in the intestine (through an artifical opening,) they were not hatched. It was clear, therefore, that only the gastric juice could hatch the embryos; and this accounts at once for the strange fact, that the embryo never hatches in the intestine of the animal where the tapeworm itself lives. Moreover, he found that they do not pass from the stomach into the intestine, and hence, as had been supposed, through the bile-ducts into the liver, but that they pierce the blood-vessels, and thus come into the circulation. He even, after a long search, found four perfect embryos in the blood taken from the vena porta. It is by the blood that the embryos of tapeworms are carried to the organs in which they develop iuto hydatids. It now at once became obvious how easily they reach the muscles, the brain, the lungs, etc. But it is to be supposed that only those which reach the destined organ will develop themseves, while the rest, which are carried to other organs, must perish."

The subject is continued with a full description of the common tapeworm and of other species. The extreme length is stated by Diesing at twenty-four feet.

4. Depth of Molluscs of Peconic and Gardiner's Bays, Long Island, N. Y.; by SANDERSON SMITH. (Communicated for this Journal.) Depth. |

Name.

*Loligo illecebrosa,*

Ranella caudata,

Pyrula canaliculata,
Pyrula carica,
*Buccinum plicosum,

*Nassa obsoleta,

*Nassa trivittata,
*Columbella avara,
*Columbella Gouldiana,
Columbella lunata,
Pleurotoma cerinum,*
Pleurotoma plicatum,
*Natica heros,
*Natica duplicata,
*Natica triseriata,

Natica pusilla,*

Remarks.

Turdo, Theca, Ascidia, a Cynthia, a Molgula, two or three Aplysiæ, and six or seven Botrylli and Polyclina.

Recapitulation.-One Cephalopod, forty-three Prosibranchs, one Pulmonifer, three Tectibranchs, one Nudibranch, forty-one Lamellibranchs, and fifteen Tunicates, altogether one hundred and five marine species. Besides these, *Astarte castanea, *Cyprina islandica,* *Mesodesma arctatum, *Purpura lapillus, and *Buccinum undatum, occur on the Sound and about Montauk Point, making a total of one hundred and ten species for the eastern end of Long Island. Twenty-nine of these (marked with a after them) excluding the Tunicata, are additional to those stated by Dekay to occur in the waters of the State, though many of them are surmised by him to exist there. I have no access to a library, to determine how many have since been described as coming from them. Including the Tunicata, the number would rise to forty-three or forty-four. Sixty-two species (marked with a before them), or sixty-five per cent, (excluding the Tunicata,) pass Cape Cod. Only twenty-nine other species are stated by Mr. Stimpson, in his "Shells of New England," to pass the Cape, so that 68.1 per cent of the whole number occur here; and a little dredging about Montauk would probably discover nearly all the

others.

IV. ASTRONOMY.

1. Fifty-fourth and fifty-fifth Asteroids.-The asteroid discovered Sept. 10, 1858, by M. Goldschmidt at Paris, has been named Alexandra, and is numbered as the fifty-fourth of the series. The asteroid discovered on the same night, by Mr. George Searle at Albany, N. Y., has been named Pandora, and is numbered the fifty-fifth.

2. Another Asteroid.-In 1857, Mr. E. Schubert of Washington, undertook a series of observations of the asteroid Daphne. On computing his observations he was surprised to discover that he had not found Daphne but had observed for it a new asteroid in the neighborhood. He has computed its elements, and it is to be hoped that the body will be redetected.

3. Review of Gilliss's Astronomical Observations in Chili,* (from Gould's Astronomical Journal, 1858, p. 168).-This volume, though bearing the date of the year in which the observations were printed, has only been issued a few weeks. It contains 332 pages of observations of Mars and Venus during two oppositions of the former and inferior conjunctions of the latter, made at Santiago by Lieut. Gilliss or under his superintendence. These series comprise both micrometric comparisons with the equatorial, and absolute determinations with the meridian circle. These are followed by 69 pages from the Washington Observatory, containing a description of the equatorial and a series of micrometric observations by Mr. Ferguson of each of the four oppositions or conjunctions. A portion contributed by Mr. Bond of the Cambridge Observatory contains 43 pages of observations of Mars during the opposition of 1849-50, chiefly micrometric determinations of right-ascension. Finally, Mr. Maclear, of the Royal Observatory at the Cape of Good Hope, has furnished an extensive series of micrometer-comparisons with the preselected stars, during the first opposition of Mars.

These 492 pages of observations and accompanying remarks are preceded by introductory remarks upon the origin and operations of the expedition, with a description of the instruments and method of observation employed, by Lieut. Gilliss; and by a detailed discussion of the entire mass of observations by the editor of this Journal. This discussion occupies 264 pages.

The plan of the expedition contemplated micrometric comparisons of the limbs of the planets, with stars previously selected by Lieut. Gilliss for the purpose, simultaneously made in the northern and southern hemispheres; but the extremely small number of northern observations precluded all hope of attaining any valuable addition to our knowledge of the Solar Parallax by this method.

In the earnest desire that so extended and costly a series of careful observations should not prove futile for the attainment of the desired end, a method of discussion has been employed, which, though entailing an inordinate amount of toil, seemed to afford the only adequate means of rendering the observations serviceable for the fulfilment of their design. The method may be briefly described.

The U. S. Astronomical Expedition to the Southern Hemisphere, during the years 1849-52. Vol. III: Observations to determine the Solar Parallax, by Lieut. J. M. GILLISS, LL.D., Superintendent. Washington, 1856. 4to.

A catalogue of the comparison-stars having been prepared, their declinations were obtained from a thorough examination of all the available sources, and from the combination by weights of the positions as given by the several authorities. Regard being had to the existence of any possible proper motion, the positions obtained were referred to the mean equinox of the beginning of the year in which the comparisons were made, and a final list of comparison-stars thus constructed, containing not only the declinations of each star, but the relative value of the determination.

The complete reduction of all the observations was then repeated, and the several comparisons with each star consolidated with care into a single observation, of which the weight was determined, and which was subsequently treated like an absolute determination of place, and even combined with meridian observations. Each of the four series (viz. the two Mars-oppositions and the Venus-conjunctions) was treated independently, and the error of the ephemeris considered as of the form x+y+22%, 7 denoting the time from a medial epoch. Four other unknown quantities were introduced,-two of these relating to the apparent semidiameter, one depending on the micrometer employed, and the last being the correction to Encke's determination of the mean solar parallax. The observations at each place have been independently discussed, and the several groups finally combined in series of approximate solutions by least squares.

The sequel indicates that the results afforded by the series of observations of Mars, during the opposition of 1849-50, so far surpass any of the others in precision and trustworthiness, that these, taken alone, promise a closer approach to the desired values than when combined with the three other series.

The resultant determinations of the whole discussion are as follows:

The great increase of the previously assumed semidiameter of Mars is very striking. It has proved impracticable in most cases to free the semidiameter from the possible influence of an irradiation dependent on the observer or on the telescope. The adopted value depends on the Washington and Santiago observations only. The necessity of some increase to the previously adopted value is indicated by six series of observations; being all made, during the first opposition, with the exception of the Cape of Good Hope series.

The propriety of a small diminution of the adopted diameter of Venus seems also to be distinctly and strongly pointed out.

Upon the resultant value of the parallax I am not inclined to place any great stress, but cannot refrain from expressing the decided conviction that the value obtained by Encke from the transits of Venus in 1761 and 1769 may be improved by a slight decrease; and am inclined to regard the value 8"-5000 as being in all probability quite near the truth, and that this value may be advantageously adopted.

SECOND SERIES, VOL XXVII, No. 80.-MARCH, 1859.

G.