The microscope and its revelations . ny part, and connected together by stolons of thelike substance. The central pear-shaped segment, a, isseen to have budded-off its circumambient segment (^ by anarrow footstalk or stolon; and this circumambient segment,after passing almost entirely round the central one, hasbudded-off three stolons, which swell into new segments fromwhich the first annulus is formed. Scarcely are any two * Although the above may be considered the typical form of the Orbitolite,yet, in a very large proportion of specimens, the iirst few zones are not com-plete circles, the e
The microscope and its revelations . ny part, and connected together by stolons of thelike substance. The central pear-shaped segment, a, isseen to have budded-off its circumambient segment (^ by anarrow footstalk or stolon; and this circumambient segment,after passing almost entirely round the central one, hasbudded-off three stolons, which swell into new segments fromwhich the first annulus is formed. Scarcely are any two * Although the above may be considered the typical form of the Orbitolite,yet, in a very large proportion of specimens, the iirst few zones are not com-plete circles, the early growth ha^Tug taken-place rather in a spiral than in aradial direction; between these two plans, there is everj variety of gradation;and even where the spiral is most distinctly marked in the first instance, theadditions soon come to be made in concentric zones. 510 POKAMINIFERA, POLYCTSTINA, AND SPONGES. specimens precisely aKke, as to the mode in which the firstannulus originates from the cii-cumambient segment; for Fig. Composite Animal of simple type of Orbitolites complanatus :—a,central tiiass of sareode; b, circumambient mass, giving off pedmicles,in which origiQate the concentric zones of segments connected byannular bands. sometimes a score or more of radial passages extend them-selves from every part of the margin of the latter (and this, ascorresponding with the plan of growth afterwards followed, isprobably the tyincal arrangement), whilst in other cases (as inthe example before us) the number of these primary offsets isextremely small. Each zone is seen to consist of an assem-blage of ovate segments, whose height (which could not beshown in the figure) corresponds with the thickness of thedisk; these segments, which are all exactly similar and equalto one another, are connected by annular stolons ; and eachzone is connected with that on its exterior, by radial exten-sions of those stolons, passing-off between the segments.—Although no opportunity has
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