REPORT ON THE RADIOLARIA. 



409 



ing the latter with the former. In the Phacodiscida and Coccodiscida the capsiile 

 encloses the simple or double medullary shell, but is itself enclosed by the cortical phacoid 

 shell. In aU C y c 1 o d i s c a r i a (in the Porodiscida, Pylodiscida, and Spongodiscida) 

 the capsule fills out the greatest part of the chambered or spongy skeleton, and is only 

 protected by the superficial parts of it, in the Porodiscida and Pylodiscida by the cover- 

 ing sieve-plates, in the Spongodiscida by the spongy cortical substance of the shell. 

 The growth of the capsule corresponds to that of the including shell, gradually increasing 

 on the margin in the equatorial plane. Whilst in the greater number of D i s c o i d e a its 

 form continues circular, in many forms provided with radial arms it enters into the arms 

 and assumes their form. The protoplasm of the capsule is commonly coloured by brown 

 or red pigment, and often contains many oil-globules. The nucleus is originally enclosed 

 by the medullary shell or the central chamber, and with increasing size enters into the 

 surrounding parts ; in the Cyclodiscaria it often fills out the internal concentric 

 rings. The extracapsular jelly or the calymma is commonly thick, and envelops the 

 greater part or the whole body. 



Synopsis of the Families of the D i s c o i d e a. 



I. Section 



Phacodiscaria. 



Discoidea with external 

 phacoid shell (or len- 

 ticular latticed cortical 

 shell). 



II. Section 



Cyclodiscaria. 



Discoidea without external 

 phacoid shell (no len- 

 ticular latticed cortical 

 sheU). 



Phacoid shell simple, without enclosed medullary shell, 



f Margin without chamhered 



Phacoid shell with simple | girdles, 

 or double enclosed medul- -j 



lary shell. | Margin surrounded by cham- 



[ bered girdles. 



Surface of the shell covered 

 by convex or even por- 

 ous sieve-plates (not 

 spongy). 



Concentric rings around the 

 central chamber complete 

 (without open spaces). 



Concentric 

 central 

 rupted 

 spaces. 



rings around the 

 chamber inter- 

 by three open 



Surface of the shell 

 porous sieve-plates, 



spongy, not covered by peculiar 



1. Cenodiscida. 



2. Phacodiscida. 



3. Coccodiscida. 



4. Porodiscida. 



5. Pylodiscida. 



6. Spongodiscida. 



Family XVIII. Cenodis cid a, n. fam. (PL 31, fig. 11; PL 48, figs. 1-3). 



Definition. — Discoidea with simple extracapsular phacoid shell (or lenticular 

 latticed cortical shell), without medullary sheU and without chambered equatorial 

 girdles. 



The new family Cenodiscida opens the long series of D i s c o i d e a, as their most 

 simple and primitive form. The circular lenticular central capsule is enclosed by a 



(ZOOL. CHALL. EXP. — PART XL. — 1885.) E^ 52 



