132 PEOF. p. M. DTJJfCAT^ ON THE STRUCTUEE AND 



larger form. The cycle of costse without septa and the small 

 second cycle of septa are common to both forms. In Mr. Tomes's 

 species there are gibbosity and dome- shaped prominences of the 

 massive coral ; and it is evident that those conditions bring the 

 form, the septa and costse being the same, within my species Oya- 

 tJio]Dliora tuberosa as a well-marked variety. 



CyatJiopliora tuberosa, nobis, will retain its generic title. Mr. 

 Tomes states that this species bears so close a resemblance to 

 C. luciensis, Ed. and H., that it may probably prove to be identical 

 with it. The distinction is evident, and consists in the absence of 

 the third cycle of septa in C. tuberosa ; the tuberose form is also 

 specific, as is likewise the distance between the decidedly raised 

 calices. 



Cyathophora Pratti, Ed. and H., was not at first appreciated 

 by Mr. Tomes ; for he referred some corals to it, according to his 

 own statement (op. cit. p. 179), erroneously, 



MONTLIVALTIA CARTOPHYLLATA, Lmx. 



Mr. Tomes makes the following remark (op. cit. p. 180) : — " There 

 is an obvious error in the description given of this coral by MM. 

 Milne-Edwards and Haime (Hist. jSTat. des Corall. t. xi. p. 303). 

 The number of cycles given by them is five and par^ of a sixth. 

 This statement, however, has been corrected by M. de Eromentel, 

 who says, there are in a large calice as many as 162 visible septa. 

 In the calices of those I have examined there are about 108 septa." 

 Here the reference to the obvious error ends, and we are not 

 directly informed what it was ; but the inference left to be drawn is, 

 that corals liaving either 162 or 108 sejpta have not five cycles and 

 part of a sixth. Now in looking over M. de Eromentel's works, I 

 find, in his ' Introduction,' p. 117, and also in the Paleontologie 

 Frangaise (Terr. Jurass. Zooph. p. 202), that the coral has " cinq 

 cycles et rarement des cloissons d'un sixieme." The number 162 

 is mentioned as occurring in a large calice. 



It does not appear, then, that M. deEromentel corrected an obvious 

 error ; for the number of 108 septa means five cycles (96 septa) and 

 a part of the sixth cycle, that is to say five cycles and one eighth of 

 a sixth. M. de Eromentel's number of 162 septa means five cycles 

 and just over five eighths of a sixth cycle. MM. Milne-Edwards 

 and Haime were quite correct in giving the form the septal arrange- 

 ment of five cycles and part of a sixth. 



In the communication under consideration the credit is given to 

 M. de Eromentel of drawing attention to the necessity of distin- 

 guishing between fissiparity and gemmation ; and it is mentioned 

 that this author states that the corallite which is the result of fissi- 

 parity is not enclosed in a neiu and distinct wall, even when it has 

 become separated from the parent calice ! 



Now Pallas, in 1766, drew attention to the fissiparity of corals, 

 and Ehrenberg, in 1834, made fissiparity, which he thoroughly under- 



