of the Association once more to the question. In doing this, however, I shall not attempt to answer formally the objections to the report of the committee, but proceed directly to describe the two fossils indicated. The accompanying figures will aid me in conveying a correct idea of the strongly marked differences which they exhibit.

1. Description of the Atops Trilineatus.

CRUST granulated; CEPHALIC shield semicircular, with the anterior and lateral edges turned upwards; posterior angles rounded ; length and breadth of the shield as 1 to 3; glabella slightly narrowed, and turned upward anteriorly; divisions 4 or 5, and unequal ; the 4th division is marked by a sulcus, which runs obliquely downward and backward, and meeting in the median line or axis; the posterior division runs parallel with the ribs, or rings of the body, and has one protuberance upon the median line. FACIAL SUTURE; EYES, cheek shields, rounded at the posterior angles. BODY composed of 17 or 18 rings, which become narrow towards the caudal extremity; axis narrower than the lateral lobes; rings 17, and which are separated by a groove about as wide as the ring itself, and marked by a row of spinous points upon their median line; lateral lobes or ribs, 18, jointed; the first, or anterior, corresponds with the divisions of the glabella; axis of the lateral lobes marked by a strong prominence, which becomes obsolete towards the tail; rings grooved by a single and simple sulcus, which runs directly outward, but which suffers a slight interruption at the axial prominence; the caudal shield is composed of one ring, and bordered by a flat expansion of the crusts.

2. Description of the Triarthrus Beckii.

Crust smooth, semicircular parabolic, bordered by a slightly thickened edge, traversed by a groove; posterior groove terminated in a point, which turns inward, and which extends beyond the base; height and breadth as 1 to 2. Glabella rectangular on three sides, and rounded only anteriorly; length and breadth equal; dimensions 4, and marked by three oblique lines, which run from the border downwards, the last only meeting in the median line: body composed of 12 or 13 rings, whose width is one-third greater than that of the lateral lobes; spinous-like points mark the median line or axis; lateral lobes composed of 12 or 13 rings; rings marked by an oblique furrow running from the upper and inner angle to the opposite lobe and outer angle, and by a short direction, which, if continuéd, would intersect the other near the middle of the rib or joint;

C

caudal shield composed of four or five rings, and bordered by a thickening of the crust, which are marked by fine lines.

Observations.

From the foregoing descriptions, it will be observed that the proportions of the two fossils are quite different. These differences begin with the cephalic shield, and extend to the tail; not only affecting the major parts, but extending also to the minor parts, in many minute details. The dissimilarity, in fact, is so great, that I am quite unwilling to regard them even as belonging to the same genus. In the paleontology of New York, parts of the same fossil, which I have called the Atops Trilineatus, are described as the Triarthrus Beckii, or rather as Calymene Beckii. I am not, therefore, in fault, as regards the specimens from which the foregoing description has been drawn.

Remarks upon the Eliptocephalus Asaphoides.

The Eliptocephalus, although acknowledged a new and different species from any that had been described previous to the publication of the Taconic system, has been referred to the genus OLENUS. This view of the fossil, if sustained, does not affect the validity or stability of this system. Still, convinced as I am of the dissimilarity of the genera, I must avail myself of this opportunity to reassert my claim to the genus.

The Olenus has 14 joints, but the fragment of the body of the Eliptocephalus has 15 or 16 visible; and we may conclude, from appearances, that 4 or 5 are broken off; making, probably, in all, 20 joints. In this respect it is closely allied to Paradoxides. The Olenus has an axis only one-fourth the breadth of the body, while the axis or middle lobe of the eliptocephalus is nearly equal to the lateral lobes. The axis, again, of the Olenus, and of the Paradoxides also, is strong and prominent, while in the Eliptocephalus it is only slightly elevated, the distinction between the middle and lateral lobes is quite obscure and imperfect. Again, the cephalic shield is about twice as wide as high, in the Eliptocephalus, while in the Olenus it is three times as broad as high, and the glabella is only one-fourth as wide as the shield.

There are no divisions of the glabella of the Eliptocephalus, as indicated in the paleontology of New York, but on the shield there is a strong elliptical elevation, which furnishes the name to the fossil. So the margin is not reflexed as in Olenus. In conclusion, I may remark that the Eliptocephalus may belong to the family of the OLENI

DAE, as proposed by Burmeister; but it still differs too much in its cephalic shield from both the Paradoxides and Olenus, to belong to

either genus.

Thus far, and up to September, 1848, no fossil has been discovered in the Taconic rocks, which is common to the Taconic and New York systems.

The trilobite and fossils of the geologist of Vermont (Mr. Adams), which were found in the lower rocks about Lake Champlain, belong to an intercalated mass of shaly limestone, associated with calciferous sandstone, and is placed only in juxtaposition with the Taconic slates, but is never interlaminated with them, and really belongs to the New York system.

I make these remarks upon the fossils because they appear to me to be called for; but I wish it to be fully understood, that the separation of the Taconic rocks from the New York, or Silurian, is called for, and was called for, on grounds far more important than the presence of certain fossils; that evidence is found in the succession and superposition of the two systems, and in the vastness of the Taconic system, compared with the Silurian- the slates of the Taconic system being at least four times as thick as all the members of the Silurian put together.

The following communication, addressed to the Association, by Dr. JOHN W. VANCLEVE, of Dayton, Ohio, was then read by the Secretary, accompanied by the exhibition of six sheets of etched illustrations of the new species of zoophytes, described in the paper.

To the American Association for the Advancement of Science. For several years past I have employed some portion of my time in preparing a work on the "Fossil Zoophytes of Western Ohio, with a few additions from other western localities," in which all the corals of this region, that have come under my observation, shall be figured and described. I have engraved the figures, chiefly, by etching them upon copper, for printing in letter-press; so that they shall come into the pages of the body of the work, in conjunction with the descriptions. The generic characters, and those of all the species not considered new, have been translated from the work of Goldfuss, the technical description from the Latin being followed by the familiar and more extended observations from the German, with the addition of the localities in this country, and occasional remarks. In describing species believed to be new, the technical description has been fol

lowed, as in Goldfuss' work, by other remarks corresponding to those in German.

The fossils described having chiefly been found in the vicinity of Dayton, some notice of the various formations in which they occur may be proper. They consist of five successive calcareous deposits, which are exposed at various places within a distance of three miles from the town, all differing very much from each other, in general appearance, texture, colour, and in the fossils which they contain. The lowest, universally called the "Blue Limestone," corresponding with the Lower Silurian, consists of innumerable layers, varying in thickness from less than a fourth of an inch to eight inches or more, with layers of marl of similar varying thickness intervening. It is the only rock which appears at the surface in the south-western corner of Ohio, and the adjoining parts of Indiana and Kentucky. It is principally made up of bivalve shells, but contains numerous corals and fragments of trilobites and orthoceratites. The corals are of the genera Astrea, Aulopora, Ceriopora, Cyathophyllum and Retepora; and none of the species found in this formation have ever yet been found in those above it. The same circumstance is believed to be true with regard to the species of shells. The colour of the fossils is the same as that of the stone in which they are imbedded.

Upon the Blue Limestone lies a bed of marl, varying in its thickness, at different points, from ten to sixty feet. It does not include any solid rock, either in layers or fragments; being of the same composition, texture and colour, from top to bottom, although its colour varies a little at different places, at some distance from each other. No fossils have been observed in it.

On this bed of marl rests a formation of limestone, usually between twenty and forty feet in thickness, composed of the remains of a great variety of animals, intermixed with semi-crystalline scales. Sometimes, fragments of encrinites constitute almost half the mass. The colour is variable; in some places nearly white, in others reddish, in others dusky brown; but it is most frequently of a wax yellow, and the formation is usually termed the "Yellow Limestone." The fossils found in it, besides the encrinital remains, are chiefly corals, with a very few shells and trilobites. The corals are generally in excellent preservation, differing very little, if at all, in colour and texture, from recent specimens. Their colour is of a bony whiteness, not being influenced by that of the rock in which they occur, whether white, red, brown or yellow. They are of the genera Astrea, Catenipora, Cellepora, Cyathophyllum, Eschara, Favosites,

Flustra, Gorgonia, Lithodendron and Retepora. Of these genera, none of the species found in this formation are seen in either of those above or below it, except the Catenipora, Eschara and Gorgonia. The Catenipora is found in the Quarry Limestone, and its impressions, and those of the Gorgonia and two species of Eschara, occur in the Silicious Limestone.

Upon the Yellow Limestone rests a formation, which is usually termed the "Quarry Limestone," as on account of its superior quality, it is almost the only stone quarried in the vicinity for building purposes. It consists of several layers, easily separated from each other, making an aggregate thickness of about four feet, which it is not known to exceed. It is of a light grey colour, and very hard and compact. The fossils which it contains differ but little in colour from the stone, and are so completely enveloped in it, that they are not easily found. The genera that have been observed are Astrea, Catenipora, Favosites, Sarcinula and Syringopora. The species are all peculiar to this formation, except those of the Catenipora, as mentioned before.

The Quarry Limestone is covered by a formation of "Silicious Limestone," in which the silicious matter, in fine grains, constitutes about fifteen per centum. The rock has the colour of ashes. It is six or seven feet thick, near Dayton; but as it extends to the north and east, the thickness increases to fifty or sixty feet. It usually contains only the impressions of fossils, the whole substance of the shell or coral having, in most cases, disappeared. The corals, of which impressions are left, belong to the genera Catenipora, Coscinopora, Eschara and Gorgonia.

To the last three formations, collectively, DR. LOCKE, in the Ohio Geological Reports, has applied the general designation, "Cliff Limestone." They do not pass imperceptibly into each other, by a gradual alteration of colour, texture and general appearance; but the change is immediate and total, the lines of separation being definitely marked; and the fossil characteristics, with the exceptions already mentioned, are also entirely different.

The gravel, in the beds and banks of the streams, and in the neighbouring hills, affords a great variety of fossils. Although the principal part of it is derived from the limestone of the vicinity, a very considerable portion of it is made up of pebbles which have a different origin. These consist of fragments of primary rocks, of all the various kinds seen in the boulders scattered over the country, and of numerous fossiliferous varieties of calcareous and silicious rocks, the