DESCRIPTION OF CHALK CORALS. 249 
fera’, a Norwegian coral, respecting which additional information is much de- 
sired. On the contrary, the cavities in the chalk fossil (figs. 14 & 16) differed 
considerably in capacity, the largest being nearly 5 lines in diameter, and the 
smaller scarcely one ; every intermediate measurement also occurring, and pro- 
ving that upward development was attended very generally by great increase of 
transverse area. Occasionally however the horn-like branches had, to the extent 
of their production, nearly cylindrical cavities. The terminations of the stellated 
hollows, and the interior of those deprived of the lamelle exhibited likewise 
marked inequalities. The smaller often presented an inner radiated area, sur- 
rounded more or less completely by a not uniform zone, which had again its outer 
boundary. The zone was sometimes structureless (figs. 19 & 22, mag.) ; but in 
other instances it was wholly lamellated (f. 26) or the inner star had perished (f. 23), 
leaving a cylindrical hollow, environed by a circle of narrow, radiating plates. 
Several of the larger cavities, though empty in the upper part, retained in the 
lower similar structures, or exhibited on the sides inequalities which indicated 
their former existence (figs. 15 & 16). It is believed that nothing analogous to 
what has just been noticed exists in true Oculine. 
Ehrenberg? states that in that genus, ‘‘ gemme non ex appendicibus pallii seu 
stolonibus prodeunt, sed ex ipso tubulo intumescente :” Mr. Dana? says, ‘‘ Each 
bud is for a time at the apex, but it gradually becomes lateral, and then gives off 
another bud from its upper side ;” and Mr. Gray’, that in Oc. avillaris they are 
emitted from each edge of the cell; while in Oc. prolifera one or two buds are 
produced from one side of the animal, and in Oc. virginea as well as Oc. hirtella 
“the cell at the tip is the one last developed.” These statements prove that in 
Oculina each polype, including in the term all animal structures in addition to 
those of the abdominal cavities, produces but one or two buds, at or towards the 
upper portion of the parent ; and though in incrusting specimens, such as those 
figured by Esper (Joc. cit. ante), there is an appearance of pallial developments, yet 
the cavities were most probably formed during the upward growth of the animal 
around the incrusted body, and not in the mantle which subsequently invested 
the coral’s outer surface. The chalk fossil exhibited two processes in every 
specimen examined’. By one of them the addition was effected at the upper 
* Consult Ellis and Solander’s Zoophytes, or Lamouroux’s Exp. Méthod, tab. 32. f. 2; also Esper, 
op. cit. Madrep. tab. 11. 
* Beitriige, p. 78, note. * Explor. Exped. Zoophytes, pp. 67, 391. * Op. eit. p. 126. 
° Other genera of Anthozoa, as the Siderastrea of De Blainville, have also two similar processes ; 
