REPORT ON THE RADIOLARIA. 627 



Genus 278. Larnacostupa, 1 n. gen. 



Definition. L arnacida with spongy lentelliptical cortical shell, with radial 

 spines, on the surface. Medullary shell double, Larnacilla-shnped. 



The genus Larnacostupa differs from the preceding Larnacospongus only in the 

 possession of radial spines, covering either the whole surface irregularly or disposed in 

 a certain symmetrical order. 



1. Larnacostupa octacantha, n. sp. 



Cortical shell lentelliptical, with thorny surface, and rather dense, irregular, spongy framework, 

 which arises from an inner latticed cortical shell, like that of Tetrapyle or Pylonium. This latter 

 is twice as large as the enclosed Larnacilla-shen. Eight long and thin, cylindrical, radial spines, 

 opposite in pairs in two diagonal planes. (Seems to be the common Tetrapyle octacantha, enveloped 

 by an outer spongy framework mantle.) 



Dimensions. Length of the whole shell (without spines) 0'22, breadth 016 ; length of the 

 medullary shell 0'06, breadth 0'04. 



Habitat. Indian Ocean, Madagascar, Eabbe, surface. 



2. Larnacostupa spinosa, n. sp. 



Cortical shell lentelliptical, about one and a half times as long as broad, with very lax and 

 irregular spongy framework, arising from a nearly quadrangular lattice-shell like that of Tetrapyle ; 

 this latter encloses a Larnacilla-shell of half its size. Whole surface covered with thin bristle-like 

 radial spines, of about the length of the shell. 



Dimensions. Length of the whole shell (without spines) 018, breadth 012 ; length of the 

 medullary shell 0'05, breadth 0'035. 



Habitat. Antarctic Ocean, off Kerguelen, Station 150, surface. 



3. Larnacostupa dendrophora, n. sp. 



Cortical shell nearly spherical, scarcely longer than broad, with lax, irregular spongy frame- 

 work, arising from a lentelliptical trizonal medullary shell (like Larnacilla). Whole surface 

 covered with thin arborescent radial spines, about half as long as the shell, each spine with three 

 to six irregular branches. 



Dimensions. Length of the whole shell (without spines) 015, breadth 013 ; length of the 

 medullary shell 0'07, breadth 0'04. 



Habitat. Antarctic Ocean,. Station 154, surface. 



1 Larnacostupa = Chest with hemp envelop; x{>J, m\nci\. 



