REPORT ON THE RADIOLARIA. 351 



stout, conical, slightly sulcatod, about as long as the breadth of the cortical shell, as broad at the 

 base as the medullary shell. 



Dimensions. — Length of the cortical shell 0'2, breadth 013 ; thickness of the spongy wall 0'045 ; 

 diameter of the medullaiy shell 0'04. 



Hahitat. — Fossil in the rocks of Barbados, Ehrenberg ; living in the Equatorial Atlantic, Station 

 348, depth (2450) fathoms. 



2. Spoagatractus fiisiformis, u. s]3. 



Cortical shell one and a third times as long as broad, with nearly smooth surface. Spongy 

 framework very compact, with very small meshes, about as thick as the radius of the spherical 

 medullary shell. Polar spines very strong, three-sided pyramidal, about as long as the breadth of 

 the cortical shell, as broad at the base as the medullary shell. 



Dimensions. — Length of the cortical shell O'lG to 018, breadth 012 to 014; thickness of the 

 spongy wall 0-02 ; diameter of the medullary shell 0'04. 



Hahitat. — Pacific, central area. Station 268, depth 2900 fathoms. 



3. Spongatractus streptacantlms, n. sp. 



Cortical shell twice as long as broad, with thorny surface. Spongy framework loose, with large 

 meshes, about as thick as the ellipsoidal medullary shell. Polar spines very long, three-sided 

 prismatic, with three spirally contorted edges, much longer than the cortical shell, half as broad 

 as the medullary shell. 



Dimensions. — Length of the cortical shell 0-25, breadth 013 ; thickness of the spongy wall O'OS ; 

 diameter of the medullary shell 0'03 to 0'04. 



Habitat. — North Atlantic, off Canary Islands, Haeckel. 



Genus 150. Spongolwa,^ n. gen. 



Definition. — S p o n g u r i d a with spongy ellipsoidal cortical shell, enclosing a 

 double, spherical or ellipsoidal, latticed medullary shell. Polar spines absent. 



The genus Spongoliva differs from the nearest Spongodrnppia by duphcatioD of 

 the medullary shell ; it bears therefore the same relation to this that Pnimihim does to 

 Drupjmla, and can be regarded as a Prunidum, in which the simple latticed cortical 

 shell is replaced by a spongy framework. 



Subgenus 1. Spongolivetta, Haeckel. 

 Definition. — Surface of the shell smooth or rough, without radial spines. 



Spongoliva = Spongy olive ; o-woVyo;, cAeia. 



