A. EARLAND ON RADIOLARIA. 283 



Fig. 1a. Central capsule of Thalassoplancta brevispicukCf. 

 Haeckel, a Radiolarian of the First Legion (Spumellaria). 



The central nucleus includes many nucleoli. The sarcode is 

 divided up into innumerable clear vacuoles, and in the cortical 

 zone and close to the capsule membrane there is a layer of large 

 oil globules. The alveolate calymma is shown in the lower half 

 of the figure, x 50 diameters. 



Fig. 2. A Radiolarian of the Second Legion (Acantharia) , 

 Lithoptera quadrata, Haeckel. In the Second Legion the skeleton 

 is centrogenous, and in the figure the central part of the skeleton 

 can be seen enveloped in the four-lobed central capsule, x 150 

 diameters. 



Fig. 2a. Equatorial section through the central capsule of 

 Zo7iaspis cingidata, Haeckel, a Radiolarian of the Second Legion 

 (Acantharia), showing the spines of the centrogenous skeleton 

 radiating from its centre, and the intra-capsular xanthellte 

 peculiar to this legion. X 205 diameters. 



Plate 16. 



F'ig. 3. A Radiolarian of the Third Legion (Nassellaria),^ 

 Cyrtocalpis urceolus, Haeckel. The siliceous skeleton encloses an 

 ovate central capsule, which exhibits at the basal pole the striated 

 podoconus, and in the upper half a large spherical nucleus and 

 oil globules. Between the capsule membrane and the skeleton 

 are many xanthellas, some of which have been extended through 

 the shell mouth along the radiating pseudopodia. x 265 

 diameters. 



Fig. 3a. Central capsule of Tripterocaljns ogmoptera^ Haeckel, 

 a Radiolarian of the Third Legion (Nassellaria), showing in the 

 centre the podoconus, a feature peculiar to this legion. On its 

 right is the large kidney-shaped nucleus, and above it are several 

 oil globules. x 160 diameters. 



Fig. 4, A Radiolarian of the Fourth Legion (Phseodaria), 

 Challengeria murrayi, Haeckel, seen from the dorsal side. The 

 oral portion of the skeleton shows the hexagonal " diatomaceous" 

 markings characteristic of the Family Challengerida. In the 



