240 DESCRIPTION OF CHALK CORALS, 
affords no assistance. If the simple species were adopted, the genus would con- 
tain only one of those originally described by Lamarck, and that authority would 
appear in subsequent works on zoophytes to have but little claim upon atten- 
tion ; whereas if the group characterised by a fissiparous process be selected in 
conformity with the systems of Herr Ehrenberg and Mr. Gray, Lamarck’s share 
in the genus would be prominent ; and Caryophyllia would moreover rest on a 
very decided as well as all-important physiological character. 
The foregoing remarks have been intruded upon the reader to explain, why 
simple, fixed corals are not considered the representatives of Caryophyllia ; and it 
is only with such polyparia that the chalk fossil admits of comparison. 
The Cyathina of Ehrenberg', founded on Caryophyllia cyathus, is characterised 
by simple lamellz, and the terminal star having a circle of small plates or pro- 
jecting points between the outer lamelliferous zone, and the central contorted 
structure: it consists also, as previously stated, of simple stems permanently 
fixed ; and the exterior is not covered by the polype, except immediately adjacent 
to the upper margin ; and there only when the animal is extruded. One of Ehren- 
berg’s essential characters is the central structure of the terminal cavity, parti- 
cularly the circle or crown of projecting points (consult remarks op. cit. p. 77) ; but 
he says, ‘“‘ apud Madreporas tales coronze frequentes sunt, rariores apud Astreeas 
et Favias inveniuntur ”’ (Joc. cit.). Mr. Dana? refers directly to Ast. pentagona as 
having such a circle; and the structure exists in Cladocora cespitosa (Caryophyl- 
lia id., Lamarck). A similar character is also visible in a variety of Oculina 
pallens of Ehrenberg (Oc. hirtella of Lamarck, as represented by Esper, op. cit. 
tab. 14). The structure appears to vary considerably in different species, and 
even in specimens usually assigned to Cyathina (Cary.) cyathus, presenting some- 
times rounded plates (Esper, tab. 24), sometimes sharp spines (Sol. & Ellis, tab. 28, 
f.7)°. Such a circle moreover, from the statements of Ehrenberg and Mr. Dana, 
and from the instances mentioned above, cannot be regarded by itself as a generic 
distinction, however valuable it may be in separating Cyathina from other simple, 
turbinated, and permanently fixed corals: it should also be remembered that the 
plate may vary with conditions of growth, being nothing more than a lobe of 
the lamella in front of which it stands. As respects the chalk fossil, out of 
1 Beitrage, p.76. Hermann describes the coral under the designation Madrepora calendula, and 
he states that it had not previously been noticed in detail, though Mercati had figured it in the Meta- 
lotheea Vaticana (1719). Naturforscher xviii. Stuck. s. 115. tab. 5. f. a, 6. 1782. 
> Explor. Exp. Zooph. p. 370. Consult Esper, Pflanzenthiere, Madrep. tab. 39. f. 1 & 2. 
* Consult Hermann, op. cit., tab. 5. f. a, 6. His description is also believed to be the fullest yet 
published: also Mr. Dana, p. 370-371. 
