DESCRIPTION OF CHALK CORALS. 267 
The depth of the terminal division of the tube, or the receptacle for the digestive 
organs was small, a point of agreement with Palmipore. Internally the tubes 
had a simple outline, ranging vertically in the expanded specimen ; but obliquely 
in the centre, and horizontally in the outer portion of branched examples. The 
transverse lamin, in the best preserved cases (fig. 39 c), were near each other, 
and thick, giving the tubes a cellular appearance ; but nothing was observed in 
any part of the coral to justify a suspicion that it was referable to the family 
Celleporide, or was formed by an ascidian polype. As before stated, lamella 
were totally wanting. M. De Blainville says the apertures of Palmipore are 
‘“ obsolétement radio-cannelée ”’ (op. cit. p.391); and to the extent observed, the 
openings of Pal. complanata as well as of Pal. alcicornis presented very slight 
traces of any structure which could be regarded as a representative of lamella, 
agreeing in this respect with the English chalk fossil. Ehrenberg did not ob- 
serve tentacula in a living specimen of Millepora (Palmip.) complanata (Beitrige, 
p. 125). The composition of the general fabric, confining the term to the net- 
work, was prevailingly slender, and penetrated in every direction by numerous 
very minute pores ; and the texture of the spinous processes, of the large warts, 
and the venous ramifications was strictly analogous. The spines were irregularly 
distributed, and often indistinct from abrasion or smallness ; and their position 
was occasionally indicated rather by the arrangement of the tubular apertures 
than by prominence of character. The warts and the ramifications proceeding 
from them (fig. 88 a) were generally, but toa variable extent, penetrated by abdo- 
minal cavities. Some of the warts were almost wholly occupied by them, though 
the amount of protuberance was not thereby markedly affected ; while, on the 
contrary, the existence of the branched structure seemed to depend on their ab- 
sence, as not an instance was observed of raised divergences except the aper- 
tures were few in number. The internal range of the last three component 
parts was not clearly ascertained. One wart traversed by a few tubes was 
progressively worn down, but no variations were observed at the different stages 
of the operation ; and a portion of a branch abraded as nearly vertical as pos- 
sible, gave a totally indistinct composition, the tubular cavities vanishing also. 
This obscurity was believed to arise from mineralization, and not from efface- 
ment by animal secretions, fractured portions of both expanded and branched 
specimens affording open tubes throughout the whole intersections. 
No cases were noticed of structurally closed apertures. 
