302 DESCRIPTION OF CHALK CORALS. 
equality ; and where irregularities existed similar to those before mentioned, the 
tubuli had an oblique position with a considerable underlay. In the central por- 
tion of the specimen the interior of the minute hollows was cylindrical ; while 
in the flattened marginal bands it was oval or compressed, and the cavity dis- 
appeared possibly altogether adjacent to the attenuated edge of the coral. As 
already stated, no apertures were visible similar to those which form the secon- 
dary pores in many genera of Bryozoa ; and as a further proof that the end of the 
tubuli was structurally shut, no distinct openings were detected in the margin of 
the large mouths, though the lines marking the boundaries of the subordinate 
structure ranged up the side of the projecting portion of the tube. The only 
means of communication between the animal matter which occupied these little 
hollows, and the visceral cavities or the exterior of the coral, was apparently 
the microscopic pores so prevalent in the integuments of Bryozoa. The portion 
shown in figure 2a bore the semblance in one part of a mechanical separation 
in the lamine of the outer bands, but the evidence was not conclusive, a similar 
appearance accompanying an irregularity plainly due to a laceration im the 
membranes of the polype. Internally (fig. 2 a) the central area was occupied by 
visceral tubes in close juxtaposition, but not arranged in two regular rows parted 
by a medial layer, nor could the opposite series be parted evenly ; nevertheless 
the tubes terminating on each surface sprang apparently from the side to which the 
openings belonged, without any interlacing, though with a clear structural blend- 
ing in the parietes. So far as the small portion exposed justified an inference, the 
underlay was very little, and the outward bent portion of the tube was also small. 
The observed surface-changes were very trifling. In the upper part of the frag- 
ment represented by figure 2*, the lines bounding the tubuli, if rightly understood, 
projected slightly, but lower down the outer covering was apparently thicker and 
on a level with the edge of the side wall; while in the lowest portion of figure 2 
the tubular outline was less distinct. 
Tab. XVIII. B. figs. 3, 4 & 5. 
The fossil about to be noticed is believed to be the Retepora flecuosa of Dr. 
Mantell' ; and M. De France? referred doubtfully to the same genus a Maestricht 
coral which exhibits in Faujas de St. Fond’s® rough delineation, some resem- 
‘ Medals of Creation, vol. i. p. 284, Lign. 64. fig. 11. 
> Dict. Se. Nat. t. xlv. p. 283, Ret.? ramosa. 
® Hist. Nat. de la Mont. de St. Pierre de Maestricht, p. 191. pl. 35. figs. 5, 6. 
