General History of the Marine Polyzoa. 93 



has correctly stated, are suberect, and the aperture slopes 

 towards the top, so as to be subterrainal ; as a consequence 

 they have a very distinctive character. The aperture is oval, 

 with a smooth raised margin, whicli is thin, except below, 

 where it is elevated and sometimes thickened. There is a 

 considerable space between the rim of the aperture and the 

 membranous covering, and the inner cell-wall here is minutely 

 speckled. The smooth porcellaneous outer wall is a striking 

 feature, but this would hardly be preserved in the fossil. 

 The cells taper downwards very decidedly, so as to be almost 

 pedunculate ; this is especially apparent in the uniserial 

 colonies. Small rudimentary cells are scattered in consider- 

 able numbers amongst the normal zooecia in the Ceylon 

 specimens, but they are not noticed by Manzoni. The cells 

 are very loosely aggregated. 



The differences which I have noted are not without signifi- 

 cance ; but in the absence of specimens of the fossil form it is 

 impossible to estimate their precise value. For the moment 

 the point may be left suh j iidice. 



Pyripora crassa *, MacGillivray, is another allied species, 

 but I cannot satisfy myself of its identity with the form 

 under consideration. " The thick projection from the lower 

 margin of the aperture," which is made a capital character of 

 P. crassa^ is not represented in Manzoni's species. Its cells, 

 too, seem to me to be much more Hippothooid in form than 

 those which I have figured. If MacGillivray's species should 

 prove to be identical with Manzoni's, his name would have 

 precedence. 



Ibid. (p. 26 Sep.). 

 Membranipora polita, sp. n. 



MacGillivray suggests that this species may be the Celle- 

 'pora alata of Lamouroux ; but there is no trace of the wing- 

 like structure from which this species takes its name, to say 

 nothing of other differences. 



[To be continued.] 

 * ' Zoology of Victoria/ decade xi. p. 23, pi. cvi, fig. 4. 



