Fossil Corals. 



211 



Ortmann^ appears, therefore, to be perfectly justified in con- 

 cluding that Edwards & Haime reversed the names of these two 

 species. 



The Christmas Island collection includes three specimens of this 

 species, which have the following dimensions : — 



"Width of calicinal series 



Number of primary septa per cm. 



They are therefore referable to the Z. tenuis of Edwards & Haime 

 (iiofi Dana) and the Z. phri/f/ia of Ellis & Solander, with whose 

 figure they agree. 



A slide cut from specimen No. 306 affects the generic diagnosis 

 of Leptoria. As generally defined, the walls of adjacent corallites 

 are said to unite directlj^ ; but, as shown on Fig. 1, the adjacent 



F;g. 1. 



series are, in places, united by costce and exotheca, and not by 

 the walls. This fact led me, on first examination of the slide, 

 to feel some doubt whether the coral were a Leptoria. But it 

 appears only necessary to modify the generic diagnosis to this slight 

 extent ; for the' same mode of union of the series of corallites 

 occurs in Z. fenuis (Dana). Thus Dana's description of that 

 species refers to the corallum as very cellular ; and his figure of 

 a transverse section (Dana, op. cit., pi. xii, fig. Id) shows the 

 compound nature of the walls. 



Mr, Bernard's manuscript list of the recent corals collected by 

 Mr. Andi'cws at Christmas Island shows that Z. phrtjgia still 

 lives on the neighbouring reefs. 



^ Ortmann : op. cit., p. 172. 



