42 SYNOPTIC COLLECTION. 



coloring matter. The calymma is pierced by the long 

 radial pseudopodia, which arise outside of the central 

 capsule. Late in the life of the adult the nucleus divides 

 into a large number of nuclei, as seen in fig. 3a, which is 

 a diagrammatic drawing of one half of a central capsule 

 of an older specimen than fig. 2, the other half being like 

 it, of course, at this stage of development. These nuclei 

 together with a part of the surrounding protoplasm are 

 transformed into the flagellate young (fig. 3b, a diagram- 

 matic view of one half of a central capsule in a more 

 advanced stage of development than fig. 3a). 



Actissa is a single form like most of the Radiolaria. 

 As has been stated, it never secretes a skeleton, but 

 many Radiolaria make silicious shells of rare beauty and 

 great complexity. The microscopic preparation (No. 47), 

 when seen under a high power, shows delicate lattice- 

 work forms known under the familiar name of Polycys- 

 tina, which was given by Ehrenberg to that part of the 

 Radiolaria described by Haeckel as the Spumellaria and 

 Nasellaria. These shells were taken from the famous 

 Polycystine marl of Barbadoes in the Antilles which 

 belongs to the Miocene period, and which is the richest 

 of all the Radiolarian deposits. 



Living Radiolaria are represented, greatly magnified, in 

 PI. 48, figs. 1,2. In fig. i, Thalassophysa pelagica? the 

 delicate pseudopodia radiate in all directions from the 

 shell. Fig. 2, Thflopilium cranoides? shows these and 

 also the basket-like form and delicate lacework of the 

 shell. 



The colonial Radiolaria are represented by Collozoum 

 inerme Hkl. (PI. 49, figs. i-io). Figs. 1-3 represent the 

 young. Here we find for the first time different kinds of 

 zoons and this differentiation in structure is suggestive of 



1 Thalassicolla pelagica in Haeckel's Monograph. 



2 Eucyrtidium cranoides in the Monograph. 



