REPORT ON THE RADIOLARIA. 



807 



of a double medullary shell (PI. 39, fig. 4). From these two genera all other forms 

 of the subfamily may be derived. 



The Central Capsule of the Druppulida is constantly ellipsoidal, larger than the 

 concentric enclosed medullary shells, smaller than the surrounding cortical shell ; it is 

 separated from the inner surface of the latter by a thinner or thicker jelly-mantle. 



Synopsis of the Genera of the Druppulida. 



Cortical shell without 

 polar appendages 



(neither solid spines 

 nor hollow tubes at 

 the poles of the main 

 axis). 



Cortical shell simple, ellip- 

 soidal. 



Medullary 

 shell simple. 



jMedullary 

 shell double. 



Cortical shell composed of ) -,, ■■ ,, 



two or more concentric V , ,, , , , 

 I shell double. 



Two opposite solid spines, 

 arising from the poles < 

 of the main axis. 



Two opposite hollow 

 fenestrated tubes, aris- 

 ing from the poles of 

 the main axis. 



shells. 



Cortical 

 shell simple, ■ 

 ellipsoidal. 



I" Surface 

 smooth, 



Surface 

 spiny, 



[ Surface 

 I smooth, 



Surface 

 spiny, 



Surface 

 smooth, 



Surface 

 spiny, 



Medullary \ ^°^^^ P"^''^' 'P'"''' *^^"''^^' 



shell simple. 1 t> n, i • i 



^ ( Both polar spines unequal, 



^[- , ,, i Both polar spines equal, 



shell double. ) -n i.i i • i 



( JBoth polar spines unequal, 



Cortical shell composed of two or more concentric shells 

 medullary shell double; both polar spines equal, 



^ ,.,,,, . , ,,. ( Medullary shell simple, 

 Cortical shell simple, ellip- j ■' '^ 



I Medullary shell double, 



131. Druppula. 



1.32. Drup2)ocmjms. 



133. Prunulum. 



134. Prunocarpus. 



13.5. Cromyodruppa. 



136. Cwmi/ocatpus. 



137. LHhatradug. 



138. Druppjalradiis. 



139. Stijlatradus. 



140. Xiphatradus. 



141. Cram i/of radns. 



142. Pij^elta. 



143. Pipettana. 



Genus 131. Druppula^ n. gen. 



Definition. — Druppulida with simple ellipsoidal, cortical shell, and simple 

 medullary shell, without spines or polar tubes. 



The genus Druppula, as the simplest form of the Druppulida, may be regarded as the 

 common ancestral form of this subfamily. It may be derived phylogenetic.illy either 



1 Dntp^itZa^ Small drupe or SjiJws-a, ripe Olive. 



