KAEAKOEAM STONES, OE SYEINGOSPHJEEID^. 5 



On the projections, whether mammilated, wart-like, papillate, tuberculate 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, but 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, whether 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 StoliczJcaria, 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 Syringosphcerice, 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 Stoliczkaria 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 bro\m under reflected light. Here and there 

 the lumen of a tube may be seen filled with calcite. (Plate III, Fig. 5.) 



