REPORT O1ST THE RADIOLARIA. 



807 



The membrane of the central capsule is commonly rather thin, and pierced by the 

 twenty radial spines, meeting in the centre of the capsule. Between these lie 

 innumerable small pores for the radiating pseudopodia ; however, in many cases (and 

 perhaps constantly) these pores exhibit a certain regular disposition. In many species 

 the central capsule encloses Xanthellse or symbiotic yellow unicellular Algae. The 

 nucleus becomes cleft very early in the majority of Dorataspida. 



I. Subfamily 



Diporaspida. 

 Each radial spine 

 with two opposite 

 primary apophy- < 

 ses; therefore the 

 whole shell with 

 forty primary 

 apophyses. 



Synopsis of the Genera of Dorataspida. 



No by-spines, 

 "With by-spine?, . 



I. Tribe 



Phractaspida. 



Twenty radial spines without lattice-plates ; 

 no parmal pores. 



349. Phractaspif. 



350. Pleuraspis. 



II. Tribe 



Ceriaspida. 



Twenty radial spines 

 all with lattice- 

 plates produced -| 

 by union of the j 

 branched apo- 

 physes of each 

 plate. 



II. Subfamily 



Tessaraspida. 



Each radial spine 

 with four crossed 

 primary apophy- - 

 ses; therefore the 

 whole shell with 

 eighty primary 

 apophyses. 



III. Tribe 



Stauraspida. 



Twenty-radial spines - 

 all or partly with- 

 out lattice-plates. 



IV. Tribe 



Lychnaspida. 



Twenty radial spines 

 all with lattice- I 

 plates (produced ] 

 by union of the 

 branched apophy- 

 ses of each plate). 



