308 PROF. p. M. DUNCAN ON THE 



more or less, together with the granulations upon the nodular 

 trabeculse. The number of synapticula on the sides of a septum 

 is considerable in some instances, and of course it varies with 

 the position of the septum in the corallum. 



Here and there are thin lamellar processes crossing a small part of 

 an interseptal loculus resembling ill-defined dissepiments. In 

 some instances they are in the line of elongate synapticulae ; but 

 inrariably a perforating annelid is close at hand. They are 

 transverse growths. ISTear the calicular centre and on the flanks 

 of the septa the granules, none of which meet across, are long, 

 large, and in linear series. Here and there the series is replaced 

 by a ridge which fits on to a similar one on the opposed septum, 

 and it is a synapticulum. 



The base of the corallum is imperforate, and the columellary 

 space is open above ; but it soon becomes interfered with by the 

 nodular processes of the innermost trabeculgeof septa. The tra- 

 beculse of the septa are arranged as if a septal lamina had been 

 perforated after its development ; they radiate on one plane, and 

 occlusion of the ioramina occurs during growth. 



The collines of this species have not a true wall, nor are the 

 calices surrounded by one. The separation is incomplete, and is 

 brought about by a series of vertical synapticula, or by one more or 

 less incomplete synapticulum. The first stage to a true wall is 

 seen, as in the young of other Lophoserines (of Lophoseons, for 

 instance) ; but I'usion of the junction-processes with one another 

 does not take place in Mceandroseris Bottce. 



No one can tak^ this species for one of the Perforata, the 

 distinction being the solidity of the base and the presence of 

 solid large synapticula which close here and there the visceral 

 cavity, and which are not exaggerated granules. It links the 

 T'ungidfe on to the Perforata very decidedly, and less so, how- 

 ever, than the genus Coscinarcsa, which will be considered fur- 

 ther on. 



Mceandroseris australice, Eousseau, is the second species ; but 

 an examination of a specimen given to me some years since by 

 the late Charles Darwin, and collected by him at Keeling atoll, still 

 indicates that its septal and mural structures diflfer greatly from 

 those of the species just considered. In fact the generic attri- 

 butes of M. Bottce are very evidently those given by Housseau ; 

 but the species named M. australioB cannot belong to the same 

 genus as M.. Boita;, in spite of external appearance. It has a true 



