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BRY O ZO A

(FENESTELLIDA)

OF THE

HAMILTON GROUP.*

By JAMES HALL

FENESTELLA MULTIPLEX, 11. sp. Bryozoan, occurring only in fragments; the shape of the frond is uncertain, but probably is infundibuliform; fragments of six centimetres in width occur, evidently only a small portion of the whole frond.

Branches moderately strong, enlarging below the bifurcations, and the width just above bifurcation is .33 mm., below bifurcation .66 mm. or slightly less. The distance between the branches is variable; there are on different portions of the frond five or six branches in the space of five millimetres; on non-poriferous side the branches are angular, and have along the middle a slight keel or carina, which connects with a similar carina on the dissepiments; when the dissepiments on opposite sides of a branch are alternating, the carina of the branch, in connecting with the carina of the dissepiment, becomes zigzag, which causes the branches to appear more irregular and less rigid than on the poriferous side; the branches are smooth.

Dissepiments about .25 mm. in diameter, four in the space of five millimetres; on non-poriferous side slightly depressed, angular and carinated ; on poriferous side, depressed, rounded.

Fenestrules, on non-poriferous side, subquadrangular in outline; on poriferous side oval; length about one millimetre, width varying from one-third to two-thirds the length.

Cells in from two to four ranges, occurring as follows: In a branch which from commencement to bifurcation is six millimetres in length, for one millimetre only two ranges of cells occur, three ranges for the

* The species of the present paper only partially represent the genus as occurring in the Hamilton group. It is published in this incomplete form in order to show the progress of the work upon the Bryozoans, and to facilitate the final revision of the species.

Sen. Doc. No. 53.

space of three millimetres, and for the remaining two millimetres four ranges of cell apertures. Cells minute, circular, about 12 mm. in diameter, distant from each other equal to the diameter of an aperture, twenty in the space of one millimetre, four in the space of one fenestrule, counting those opposite the disse piment; margins distinctly elevated, and those of the outer rows indenting the border of the fenestrule; apertures sometimes alternating and forming oblique transverse rows, at other times irregularly arranged; where two rows occur the apertures open directly upward ; where three or four rows occur the central row or rows open directly upward, and the two outer rows laterally ; space between rows of apertures smooth.

Formation and localities. Hamilton group; Moscow, Livingston county, and Alden, Erie county, N. Y.

ESTELLA LATITRUNC

Bryozoan, occurring only in fragments ; the form of frond is not certainly known, but probably is infundibuliform.

Branches strong, gradually enlarging to the bifurcations; width just below bifurcation one and one-third millimetres, just above, twothirds to three-fourthe of one millimetre; the distance between the branches is from one-half to four-fifths of one millimetre; three to four branches in the space of five millimetres; on non-poriferous side the branches are slightly angular.

Dissepiments about .5 mm. in diameter, slightly expanding at their junction with the branches, two in the space of five millimetres; on non-poriferous side, on a plane with the branches, slightly arching and angular; on poriferous side slightly depressed, rounded

Fenestrules, on non-poriferous side, subquadrangular; on poriferous side oval, in outline; length one and three-fourths millimetres.

Cells arranged in from three to six ranges; cell apertures minute, circular .14 mm. in diameter, distant from each other a little more than the diameter of an aperture, sixteen in the space of five millimetres longitudinally; margins distinctly elevated, and those of the outer rows indenting the border of the fenestrules, so much so, that the margins are plainly visible from the non-poriferous side, giving a somewhat serrate appearance to the margin, alternating and forming oblique, transverse rows; the longitudinal rows are separated by a fine, slightly elevated carina; the space between the apertures, longitudinally, has sometimes a single striation.

Where fragments of this species occur, from the large branches, and the widening below the bifurcations, which, when the branches are broken off a short distance above, present a clavate appearance, they very much resemble a Thamniscus, this is especially the case where the depressed dissepiments of the poriferous side are covered with sedimeut, while the branches are not; without a critical examination it would be considered a Thamniscus.

This species can be distinguished from F. multiplex by its more robust form, and the greater number of ranges of cell apertures.

Formation and locality. Hamilton group; Ontario, Canada.

FENESTELLA FISTULATA, n. sp.

Bryozoan, broadly infundibuliform or cap shaped.

Branches slender, gradually increasing in size to the bifurcations ; bifurcations distant from five to ten millimetres; diameter of branch just below bifurcation a little less than .5 mm., above bifurcation, .33 mm. ; the distance between branches is less than the width, or about .25 mm.; from nine to eleven branches in the space of five millimetres; on non-poriferous side branches slightly angular, and having along the middle a narrow, slightly elevated carina or keel, which connects with similar carinæ on the dissepiments; when the dissepiments or opposite ends of the branch alternate, the carina of the branch, in order to connect with the carina of the dissepiments, assumes a zigzag form, and also surrounds the fenestrules with a hexagonal elevation. There is no evidence of striae or of nodes.

Dissepiments comparatively strong, .25 mm. in width, expanding at the junction with the branches, depressed on both poriferous and nonporiferous side; on non-poriferous side, carinated and slightly angular; on poriferous side rounding.

Fenestrules small, oval; length from .33 to 50 mm.,width about twothirds the length, appearing the same size on each face of the frond.

Cells in two and three ranges, sometimes the third range extends only a short distance below the bifurcation, at others nearly the whole length to the next bifurcation ; apertures, minute, circular, about .12 mm. in diameter, distant from each other less than the diameter of an aperture, twenty-five in the space of five millimetres, opening nearly directly upward ; margins distinctly elevated, but on account of the apertures opening upward, scarcely indenting the border of the fenestrule ranges of apertures separated by a narrow, slightly elevated, flexuous ridge, which is shorter and more prominent when there are only two ranges of pores present.

This species is one of the most abundant of those occurring in the Hamilton group, and its poriferous face is generally easily recognized ; from F. multiplex and F. latitruncata it is easily distinguished by its size and compactness.

Formation and localities. Hamilton group; Genesee and Erie counties, N. Y., and West Williams, Ontario.

FENESTELLA ASPECTUS, n. sp.

Bryozoan infundibuliform, undulating, frequently partially folded upon itself on a line with the branches.

Branches slender, gradually increasing in size to the bifurcations, which are distant from each other from three to fifteen millimetres; a transverse section of the branch is sub-cuneiform in outline, the widest part is on the poriferous side ; just below the bifurcation on the poriferous side the branch is about .5 mm. in width, gradually growing smaller to the non-poriferous face, where it is less than half that width ; just above bifurcation on poriferous side the branch is .33 mm. in width; ten branches in the space of five millimetres; on non-poriferous side the branches are rounded or circular, and frequently have a very narrow, slightly elevated keel or striation running along the middle, which connects with a similar keel on the dissepiments, and opposite each dissepiment is a prominent triangular node.

Dissepiments slender, about .25 mm. in diameter, eight or nine in the space of five millimetres, much expanded at their junction with the branches ; on non-poriferous side depressed, and with a thin, slightly elevated carina; on the poriferous side they are scarcely perceptible.

On account of the cuneiform shape of the branches, the fenestrules on the different faces of the frond have an entirely different appearance; on the non-poriferous side the fenestrules appear broadly oval, or nearly circular, a little less than ,5 mm. in length and of about the same width; the branches rapidly thicken to the poriferous side where they are contiguous or nearly so, the fenestrule generally not showing at all, and when showing appearing only as a narrow slit.

Cells in two or three ranges, two ranges occur for only a short distance above the bifurcation, the greater part of the branch being occupied by three ranges; apertures small, circular, about .16 mm. in diameter, closely arranged, frequently nearly contiguous, twenty-eight in the space of five millimetres, the central row opening directly upward, the two outer rows nearly upward, slightly lateral; margins distinctly elevated and unusually thick; the margins of the outer rows of adjacent branches are separated only by a narrow line, sometimes contiguous; the central row of apertures is elevated above the outer rows, making the branch angular.

This species is not common, and when the poriferous face is seen is easily recognized; like F. fistulata, the cells are arranged in two and three rows and the branches are nearly of the same size, but it differs in having the cell apertures larger and much more closely arranged, and the central row much elevated, making the branch angular, while in that species the branch is nearly if not quite flat, the apertures being on the same plane; the contiguity of the branches, or the poriferous face, is also a distinguishing characteristic.

Formation and locality. Hamilton group; Bellona, New York.

FENESTELLA ANGUSTATA, n. sp.

Bryozoan infundibuliform ; fronds large.

Branches of nearly the same size throughout their entire length, except immediately below the bifurcations, or increasing in size very gradually; bifurcations at very irregular distances from each other, varying from five to fifteen millimetres; width of branches from .33 to .50 mm.; distance apart less than the width of the branches ; from ten to thirteen branches in the space of five millimetres; on non-poriferous side the branches are rounded, with generally a single range of nodes along the middle; sometimes there are additional scattering nodes with indistinct evidences of striations; on other parts of the frond the nodes are obsolete, either from wearing or some other cause not apparent, and there are from three to five strong striations on a branch.

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