242 DESCRIPTION OF CHALK CORALS. 
consolidation, but traces of partial interlamellz obliteration were observed. Not 
an indication of such a process was visible in specimens of the fossil 2 inches in 
height. One other character requires consideration. Ehrenberg states, that in 
Cyathina prolification is rare, monstrous (op. cit. p. 37). Three specimens of 
the chalk coral bore one incipient lateral cavity each ; two of the cases occurring 
close to the upper margin, the other about 4 lines below it, the total height of 
the mature specimen being an inch. The largest, situated close to the margin, 
slightly exceeded a line in diameter; and the case, at a distance from an upper 
edge, exhibited but a slight excess of development, its height being only }ths of 
a line. It is not necessary at present to notice the peculiarities of these young 
cavities, but attention will be again solicited to them. 
From the preceding imperfect remarks it would appear, that the chalk zoophyte 
usually referred to Caryophyllia centralis differs from Cyathina in the absence, 
with one exception, of the circle of lobes within the terminal cavity—in the ex- 
istence of numerous transverse plates between the lamella—in a much greater 
outward covering by the animal—and in many cases of an external thickening, 
with a want of any internal filling up of the lower part. If Ehrenberg’s character 
of a crown of plates in conjunction with an isolated mode of growth may be 
considered a satisfactory generic distinction, the prevailing absence of it in the 
chalk fossil would be sufficient to justify a separation from Cyathina; and if 
there be added to it the other differences, though some of them may be regarded 
as only differences in degree, the whole taken together form an aggregate of 
dissimilarities which is believed to require another generic assignment. 
2. Turbinolia.—Respecting the continental determinations before mentioned, 
it is sufficient to state, that whether free or not in the earliest period of develop- 
ment, the chalk fossil soon became permanently fixed ; whereas a free condition 
when mature is one of Lamarck’s essential characters. That authority neverthe- 
less included in his genus corals of very different detailed construction, as T. 
turbinata and T. cyathoides', when compared with T. crispa and T. sulcata. Many 
other fossils have been subsequently added to those originally described, but 
apparently without a full consideration of the characters of the solid portions, or 
of the probable nature of the animal and its habits. Tne cretaceous fossil 
differs most materially from the species just mentioned, whether the two first or 
the two last be the objects of comparison. How far it may agree with other ex- 
tinct zoophytes assigned to the genus, is a question which does not admit at 
' Consult Fougt’s original figures, Amoen. Acad. Tomusi. tab. 4. f. 2, 3,7; and f.1, edit. 1749, re- 
ferred to by Lamarck. 
