KAEAKOEAM STONES, OE SYEINGOSPHA]EIDA]. 
6 
On the projections, whether mammilated, wart-like, papillate, tuherculate or granular, 
there are markings to he seen which are of two kinds. On the top or centrally are circular 
markings, few or many, which on careful examination turn out to be the openings of tubes. 
They are often very minute, and their caliber is smaller than that of the tubes seen in the 
interspaces just alluded to. On the sides, and converging to the margins of the top of the 
eminences, are numerous close, straight lines, usually continuous, hut sometimes wavy, broken 
and bifurcate. They are, according to the condition of the fossil, either the preserved calcite 
of converging tube interspaces, or they may be the walls of the tubes themselves, or both. 
These tubes may be traced on the surface to be continuous with some of those of the spaces 
between the projections, to appear from within the fossil and to run up outside the eminences. 
In many instances they open, finally, at the surface around those smaller ones which appear 
in the centre of the top. 
In some forms, especially where the eminences are broad and low, these converging tubes 
open all over the projection. 
It is evident that the projections, wdiether they are simple or compound, are made up of 
the outsides of tubes, tube openings, and of calcite which fills up the interspaces between 
them; there being much bifurcation and side inosculation of the tubes also. The projections, 
mammilation or granulate tube openings and convergings belong to a radial tube series, 
and the tubulation between these eminences to an interradial series. No coenenchyma or 
skeleton exists. 
The pores are spaces in the superficial interradial tubulations, but in rare instances they 
are found elsewhere. They are surrounded and limited at their margin by tubes bounded 
within by others, and their shallow floor has the outward openings of deeply-seated tubes on 
it. The distinction between the interradial tube reticulation and the radial tube series is best 
seen in the genus Stoliczharia, on account of the definite intervals, without pores, which 
exist between the granules containing the end of the radial series. It is well seen in the 
pore bearing SyringospJi(BricB, which have distinct eminences, and it is the least apparent in 
some spheroidal kinds, where there is as much space occupied by pores as by eminences. 
The relative positions of the radial and interradial series of tubes, and the close and con¬ 
verging character of the one and the reticulate appearance of the other, must be kept in mind 
as this description proceeds, for they have the same definite relation within the fossil. In 
some species, moreover, the radial tubes are readily distinguished, because they are smaller 
than those of the interradial series. 
This persistence of the radial series of tubes, and the environing interradial and reticulate 
tubulation, can be well seen in tangential sections of those types in which the structure is 
close; for instance, in Stoliczlcaria granulata, especially if the thin slice is taken rather close 
to the surface of the body. Then a number of star-shaped masses are seen, separated from 
one another by a denser structure. The centre of the star contains small tubes cut across, 
and giving off small branches to the outside and separating structures, which consist of sec¬ 
tions of larger tubes made in different directions, such as oblique, transverse, and longitudinal. 
The small tubes of the centre of the star are well separated from each other, except where 
they bifurcate, but the surrounding tube reticulation is close, the tubes being nearly in con¬ 
tact. Clear calcite fills the spaces between the small tube ends of the star, and there is less 
of it amongst the large tubes around. The opacity of the calcareous structure of the walls is 
evident, and they are usually brilliantly white or brown under reflected light. Here and there 
the lumen of a tube may be seen filled with calcite. (Plate III, Eig. 5.) 
B 
