STEGANOPORELLA. 



177 



In external appearance the cell of Steganoporella re- 

 sembles A^ery closely that of Micropora ; but in many cases 

 the large foramina in the front wall allow the neck-like 

 termination of the lower chamber to be seen^ and so reveal 

 the structural difference between them. 



At a short distance from the upper extremity of the 

 zocecium a diaphragm shuts off the lower portion of the 

 cavity, and forms a chamber in which the polypide is 

 lodged. From the centre of this diaphragm a tubular 

 prolongation passes upwards to the opening of the cell 

 (in S. Smittii), and is there closed by the opercular 

 valve. In S. magnilahris this tubular passage (through 

 which the polypide issues from its dwelling) opens into a 

 large chamber occupying the upper portion of the cell, 

 and probably ooecial in character, which is closed in by an 

 operculum of unusual size and structure. 



The peculiarities of the last-named species connect 

 themselves with the remarkable modi- 

 fication of the ovicell, which has no 

 existence in other members of the 

 group. In S. Smittii, for instance, the 

 ooecium is of the ordinary kind ; the 

 upper chamber is wanting, and the 

 tubular passage from the lower cham- 

 ber extends to the orifice of the cell 

 (woodcut, fig. 7) . 



Fig. 7. 



The name selected for this generic 



Sections of the zooeeium. 



group is intended to connect it with the Steganopora of 

 D'Orbigny, but there seems to be no real analogy of 

 structure between the two. 



