JOURNAL 



OF THE 



ROYAL MICROSCOPICAL SOCIETY. 



JUNE, 1880. 



TRANSACTIONS OF THE SOCIETY. 



Xr. — On a Parasitie Sponge of the Order Calcarea. 

 By Prof. P. Martin Duncan, M.B. (Lond.), F.R.S., V.P.R.Hr.S. 



(_Read 10th March, 1880.) 

 Plate X. 



There is a large, coarsely growing Foraminifer on the reefs at the 

 Mauritius, which Mobius has called Garpenteria raphidodendron. 

 It has a very coarse nummuline structure, its chambers are large 

 and superimposed, and the surface is somewhat irregular from its 

 special mode of growth. Covering much space for a Foraminifer, 

 it encrusts the previous inhabitants of the surface upon which it 

 extends ; and other Foraminifera, especially Pohjfretme, and Polyzoa 

 and Serjndie, are seen to occupy its base. The upper surface is, on 

 the other hand, crowded with minute Foraminifera, Nullipores, 

 worm-tubes, and confervoid-looking plants. Evidently a rapid 

 and acervuline grower, the Foraminifer has included within and 

 between its chambers some of the minute forms which had lived 

 for a while on its surface, and it is perforated here and there by 

 multitudes of Thallophytes. 



Specimens of Cai'penteria raphidodendron were given by its 



EXPLANATION OF PLATE X. 



Fig. 1. — Mbbimisfoniji'i pirasitica within Carpenteria raphiJodetidron , magiiilictl. 

 Normal breadtli of the parent sac -, i ^^ inch. 



Fig. 2. — A free specirain witli tiie body und commencing i-tulons, niiigiiificil. 



Fio. 3. — A portion of a .specimen within tlio Carpenteria, miignitietl. 



Fig. 4. — Highly magnified surface of a .stolon-tube, .showing the cellular 

 element, the liglit-tran.smitting ispots, and the large wpinulcs. 



Fig. 5. — Portion of the .same : the clark ceils are the bases of nascent spinules. 



Fig. ti. — SpinulcM and minute spinules, mugnilied. 



Fig. 7.^The c( Us and the refractive s[)ots wliicii are abstdute penetrations, 

 mngnified. 



Fig. 8. — Tiio perforations and a delicate spicule in a sp( cimc n which is free 

 in the Canada balsam. Figs. 4 to 8 inclusive are magnified about :?0U <ii;imeters. 



Fig. 0. — Some of the spiculi!.^, raagiiilicd. 



Fig. 10. — .\ large sac from aiKjtlier Carpenteria, magnified. 

 VOL. III. ^ 'i 



