. The microscope and its revelations. FIG. 630.—A, piece of Niiuniuditic limestone from Pyrenees,showing Nummulites laid open by fracture through medianplane ; B, Orbitoides. fossil examples of the genus, and which shows no fewer than ten convo-lutions in a fragment that does not nearly extend to the centre of thespire. This section also shows the complete inclosure of the olderconvolutions by the newer, and the interposition of the alar prolonga-tions of the chambers between the successive layers of the spirallamina. These prolongations are variously arranged in different. FIG. 631.—Vertical
. The microscope and its revelations. FIG. 630.—A, piece of Niiuniuditic limestone from Pyrenees,showing Nummulites laid open by fracture through medianplane ; B, Orbitoides. fossil examples of the genus, and which shows no fewer than ten convo-lutions in a fragment that does not nearly extend to the centre of thespire. This section also shows the complete inclosure of the olderconvolutions by the newer, and the interposition of the alar prolonga-tions of the chambers between the successive layers of the spirallamina. These prolongations are variously arranged in different. FIG. 631.—Vertical section of portion of Nintnnidites Icevigata : a, margin6f external whorl; b, one of the outer row of chambers ; c, c, whorl investedby a , (I, one of the chambers of the fourth whorl from the margin ; e, <•,marginal portions of the inclosed whorls; /, investing portions of outerwhorl; g, </, spaces left between the investing portion of successive whorl* ;h, h, sections of the partitions dividing these. examples of the genus ; thus in some, as J. distant, they keep theirown separate course, all tending radially towards the centre: inothers, as .T. /trr!</nt«, their partitions inosculate with each other, soas to divide the space intervening bet \veen each layer and the nextinto an irregular network, presenting in vertical section the appear-ance shown in fig. 6,U ; whilst in .A, yarfinsciixis they are broken NUMMULITES 833 up into a number of chamberlets having little or no direct communi-cation with each other. Notwithstanding that the inner chambers a
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
