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Finally, the Council made nominations of several distinguished persons to be chosen Foreign Honorary Members and Associate Fellows.

On motion of the Vice-President, it was voted that the Chairman of the Rumford Committee be authorized and directed to reclaim the possession of the die of the Rumford medal, now deposited at the United States Mint, Philadelphia, and to place it in the safe of the Academy.

Appropriations were voted, -On motion of the Treasurer, of twelve hundred dollars for general expenses during the current year;

On motion of the chairman of the Committee on Publications, of fourteen hundred dollars for printing the Academy's publications;

On motion of the chairman of the Library Committee, of eight hundred dollars for the purchase of books and other expenses of the library.

The annual election was held, and the following officers were chosen for the ensuing year:

JACOB BIGELOW, President.

DANIEL TREADWELL, Vice-President.
ASA GRAY, Corresponding Secretary.
S. L. ABBOT, Recording Secretary.
J. P. COOKE, Librarian.

EDWARD WIGGLESWORTH, Treasurer.

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15

HENRY W. TORREY,

ROBERT C. WINTHROP,

of Class III.

The Standing Committees, nominated by the President, were elected as follows:

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Professor C. W. Eliot presented a memoir by F. H. Storer and himself on the Impurities of Commercial Zinc, with special reference to the residue insoluble in dilute acids, to Sulphur, and to Arsenic.

The Corresponding Secretary presented, from the authors, the following paper:

Description of two new Genera and eight new Species of Fossil Crinoidea, from the Rocks of Indiana and Kentucky. By S. A. CASSEDAY and S. S. LYON.

DICHOCRINUS, Münster.

In a résumé of this genus by MM. De Koninck and Le Hon, they state that, up to the appearance of their work,* only three species of this genus had been described; they add six, which, together with eleven described by American geologists, make in all twenty species. This comprises all the species of which we have any personal knowledge.

Heretofore much uncertainty has existed as regards the number and disposition of the radials and the arms. De Koninck and Le Hon give the following formula:

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Dr. B. F. Shumard, in some remarks about this genus, states as follows:-"The anatomical structure of a very perfect specimen of this genus corresponds only in part with the above formula. In our fossil we find a base of two pieces, supporting a circle of five large radials and one large anal piece, as in all known species of this genus. The radials however, are not repeated, but each one immediately gives rise to two brachial pieces, which are pentagonal, and in turn support, each, two simple arms; so that the number of the latter amounts to twenty."†

The Messrs. Austin, who up to this time have figured the most perfect examples of the genus, represent the number of radial pieces to be twenty, i. e. " five repeated four times."

"In D. ovatus there appear to be but ten, i. e. five repeated twice;

*Recherches sur les Crinoides.

† Trans. Acad. St. Louis, Vol. I. No. 1, p. 71.

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while in D. cornigerus and D. sexlobatus, now described for the first time, the whole number of radials is only five."

In a number of well-preserved individuals of D. polydactylus, we have always found three radials, and on examination of other species we have concluded this to be the number most frequently met with. The following list contains all the species of Dichocrinus which show in a satisfactory manner all the radial pieces.

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D. simplex also will doubtless show three radial pieces when perfect examples are found; D. cornigerus differs from other species in having two brachials coming immediately from the primary radial.

This is the only species showing satisfactorily such an arrangement. Shumard quotes, above, D. ovatus as having two radials repeated five times, yet in his description of the species (Owen and Shumard, Geol. Survey of Iowa, &c., p. 590) he says, "Several joints of the arms remain attached to one of the superior plates, in the only specimen we have been able to procure. The first joint is of a rectangular form, and supports a cuneiform joint, on the bevelled edges of which is the commencement of the two series of smaller plates." The formula for the radial pieces will be,

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Arms. But few specimens have been figured preserving the arms. They generally come off in five pairs, often bifurcating below, until they attain even to the number of forty divisions, as in D. polydactylus. D. fusiformis has ten arms (five pairs) without bifurcations. D. ovatus has, most probably, the same number. D. polydactylus, as we have

* Austin (Monograph of Crinoideæ, pl. 5, fig. 6, c) figures a single ray as having three small radials above the large primary radial. His specimen (pl. 5, fig. 6, b) is very imperfect, and we think it highly improbable that four radials exist in the individual there figured; such a mistake is more easily made than mistaking Dichocrinus elongatus for a Platycrinus. Hexacrinus macrostatus of the same authors has all the appearance of a Dichocrinus. (loc. cit., pl. 6, fig. 3, a.) J. Müller in his paper (Über neue Echinodermen des Eifeler Kalkes, pl. 1, fig. 3) figures a fossil which bears a most remarkable resemblance to a Dichocrinus; he calls it Hexacrinus.

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said above, has with the bifurcations 8 X 5 = 40. D. cornigerus which differs considerably from all other species, has 4 X 5 = 20. D. ficus has six pairs, 6 X 2 = 12, again bifurcating on the first joint, producing twenty-four arms or fingers. We may readily suppose that the greater number of the species of this genus have five pairs of arms, bifurcating once or more. The arms are long, fimbriated, and composed of cuneiform pieces, either in single or double

rows.

Inter-radials. Shumard is the only author who notices inter-radials. He says, that "from four to five exist in two of his species, they rest on the oblique superior lateral edges of the radial plates." They might easily be mistaken for the lower pieces of the vault.

We propose, then, the following formula for Dichocrinus :

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The vault, in all the specimens where we have seen it preserved, is large, high, and more or less ornamented with thorns and salient tubercles. This genus differs so markedly from the genera Platycrinus and Hexacrinus, both in the more elongated form, the bipartite basis, and its deep angular notch on the anal side, that it admits of an easy distinction. It approaches quite nearly to Cotyledonocrinus and Pterotocrinus, having like them a bipartite base, with a series of large pieces about it. Cotyledonocrinus has only five pieces arising from the basis, instead of six, the arms are non-bifurcate; the difference between this genus and Pterotocrinus is so marked that they cannot be confounded.

DICHOCRINUS POLYDACTYLUS, Sp. Nov.

Body. Subconoidal, resembling the ornate capitals of some composite columns, spreading rapidly from the base, the upper portion marked by prominent folds of salient tubercles. The whole of the pieces of the calyx are thin.

Vault. Surmounted by a large proboscis: column small, subrotund. Basal pieces. The two basal pieces are large, spreading rapidly

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