518 



LONSDALE ON EOCENE CORALS FROM N. AMERICA. 



A specimen of Cladocora (?) recrescens of 

 the natural size. At a the characters of 

 the side branch clearly prove that it did not 

 originate in a subdivisional process. In- 

 dications of renewed growth are exhibited 

 in the transverse lines on the cast of the 

 exterior. 



This fossil agrees in many 

 essential points, as in the 

 amount of connection be- 

 tween the branches and the 

 offsets, in the characters of a 

 the lamellae, and in the total 

 absence of external thicken- 

 ing, with the Madrepora 

 ramea, var. of Esper (Pflan- 

 zenthiere, tab. 10.), which has 

 been referred by Lamarck 

 to Caryophyllia *, by De 

 Blainville to Dendrophyllia\, 

 and by Ehrenberg, but with 

 a doubt, to Cladocora. J 

 With respect to these generic 

 assignments it may be stated, 

 that believing Ehrenberg's 

 definition of each of the 

 genera to be the best, Esper's 



coral or its fossil analogue cannot be regarded as a Caryophyllia, 

 on account of the branches being due to the development of 

 germs, and not to a structural subdivision of the polype ; nor as 

 a Dendrophyllia, on account of the total absence of external 

 thickenings. With respect to Cladocora, it can only be said, that 

 a comparison of a specimen of Esper's coral with the American 

 fossil proved an agreement in the principal characters ; but as 

 Ehrenberg doubted his generic determination that of the fossil 

 is similarly marked. The peculiarity in the renewal of growth 

 sufficiently indicates specific differences in the two polypidoms. 



The specimens of C. ? recrescens, which were examined, consisted 

 wholly of casts either of the exterior or of the internal structure, 

 but sufficient was indicated to enable the original composition to 

 be inferred. The coral probably attained considerable dimensions, 

 as the fragments ,were numerous and some portions of stems were 

 half an inch in diameter. The thickness of the outer wall was 

 universally inconsiderable, being represented by an exceedingly 

 slight interval (see figure). The proofs of its having been per- 

 forated consisted in numerous thread-like processes which crossed 

 that narrow interspace, and thickly studded also the rounded edges 

 of the casts of the intervals between the lamellae. The external 

 ribs or furrows impressed upon the matrix, were likewise occa- 

 sionally indented with small conical pits, due to tubercles on the 

 original coral. The foramina in the sides of the lamellae were 

 represented by similar filiform processes ; and the hispid projec- 

 tions on the surface by indentations in the casts of the interspaces 

 between the lamellae. The transverse lamina or diaphragms 



* Animaux sans Vertebres, 2d edit. ii. p. 353. No. 1 0. Caryophyllia cornigera. 

 f Manuel d'Actinologie, p. 354. Dendrophyllia cornigera. 

 j: Die Corallenthiere des rothen Meeres, p. 85. Cladocora ? A?ithophyllum ; 

 or Berlin Transactions, 1832. 



