ON THE OLDEST KNOWN FOSSIL, ETC. 
349 
the tiny shell may he traversed everywhere hy extremely 
minute and numerous tuhuli (like those of dentine)^ and may 
have larger tubes for larger threads or pseudopods to pass 
out^ and a larger apertm*e for the sarcode to bud forth for the 
formation of a second little lump_, connected by a stolon^,"’-’ 
or neck_, to the former ; and this^ when similarly coated with 
shelly either remaining distinct or turned back partly over the 
fii’st, may produce the hke again_, and so on in succession^, 
either in a row_, straight or cimved^ cylindrical or tapering; 
or the gemmules may form segments (more or less enveloping 
one the other) in a flat or a raised spiral form^ or otherwise ; 
and may proceed from more than one aperture in the shell. 
Not unfrequently we And Foraminifera beginning with a flat 
spiral-chambered shell (corresponding to the segmented sar- 
code) ^ and then adding chamber to chamber all round the 
edges^ and even on the upper and lower surfaces_, until the flrst 
regular stages of growth are hidden in the irregular and heaped 
(^‘^ acervuhne'’"’) growth of chambers_, or shelled segments^ on 
all sides. Conditions analogous to — nay^ even identical with^ 
these_, Dr. Dawson clearly sees in the vastly larger calcareous 
framework of his Eozoon (pi. 15^ fig. 1) ; and though so much 
larger in its accumulated chamber-growth_, row by row and 
tier on tier^ yet its intimate structure is the same^ and can be 
discerned only with the microscope power necessary to 
show that of recent Foraminifera. As in living Polytrema, 
Carpenteria, and others^ the segments of sarcode are not 
neatly divided one from another^ owing to their free manner 
of growth (chambers being scarcely marked out by divisional 
walls or septa ^^)_, so in Eozoon the sarcode did not form 
regular segments or lobules of uniform or even definite shape 
(fig. 2)j but grew out on every side luxuriantly, and only par- 
tially constricted by infoldings of the shell. Hence modified 
stolons appear, either single or multiple (passing through one- 
or several holes in a septum, fig. 4, n), or as scarcely pinched 
necks between the segments (figs. 2 and 5). 
Further, in Eozoon the shell appears in some places (at the 
base of each mass) as relatively thick laminse, white and cal- 
careous, with short, transverse, connecting lines of similar 
material (fig. 1, a) ; these shell- walls are thinner and thinner 
higher up in the fossil, for an inch or two, until both laminae 
and cross-walls are extremely attenuated, disappearing from 
sight in the greener and granular upper portion, which was at 
first thought to be a ruinous condition of the Eozoon, but is 
really its acervuhne,^^ or irregularly grown, portion (fig. 3) . 
None of this granular or finely lobulated sarcode, however, is 
really without shell; and, as Dr. Carpenter has acutely ob- 
served, it possesses the essential shell-wall as much as the 
