Lower Heldeeberg Fauk'a. 275 



Another feature of this specimen should not escape notice. 

 The gastral surface is partly covered, to the depth of 3 mm. in 

 places, by a layer of minute acerate spicules. They lie in a con- 

 fused mass and evidently are not in situ, but, since they are pre- 

 served as pyrite, like the test, they doubtless belonged to the 

 organism itself. 



Keference . has already been made to certain indications of 

 crushing exhibited by the specimen in question. In the region 

 of the basal pole the walls are held apart by the pillars, more or 

 less normal to each. They gradually approach one another and 

 their contact forms the limit of the fossil. That this is not the 

 original condition is proved by a fracture, which shows the 

 tubes lying nearly parallel with the two surfaces. Some of them 

 retain a circular section, others are flattened into an ellipse, 

 while many are broken and biconcave. (Plate III, fig. 8.) Still 

 further evidence is afforded by the condition of the outer surface. 

 Some of the tubes are there seen to have been forced up to a 

 considerable distance through the rhombic pits, and on the same 

 surface the ridges are so broken and crumpled in places that it 

 is impossible to follow them. 



Another fine specimen i& this collection is that figured by 

 Hall, in Pal. New York, vol. YI, Plate XXIY, figures 3-7.^ It 

 is probably a cast representing the inner surface of the outer 

 wall. Like most Lower Helderberg specimens it gives no 

 indication of the nature or existence of a gastral wall. The 

 radiating ridges are mostly absent or else represented by low, 

 triangular, sinuous elevations which often form circular basins 

 about the orifices of the radial tubes, instead of clear-cut 

 rhombic de[)ressions. Sometimes the points of intersection alone 

 are represented by monticules, to which reference has been made 

 by Prof. Hall. The tubes that run from the base of each rhom- 

 bic pit, form, from their size and depth, a striking feature. 



A group of individuals which come next in excellence of preser- 

 vation were found in the firmer portions of the Shaly limestone. 

 On the whole the regular reticulate nature of the surface is more 

 apparent than in that above mentioned. This is partly due to the 

 fact that although the radiating ridges are not prominent, they are 



♦This was the type specimen of iJece/jfacH/iYes mouficu/afw-s (Hall, 1883. Rep. State Geologist for 

 1882, expl. pi. XXIII, figs. 3-9, 11), before Prof. Hall considered the species a synonym of E. infundi- 

 buliformis. 



