348 THE VOYAGE OF H.M.S. CHALLENGER. 



scarcely broader than the bars. Two polar spines conical, very strong, about half as long as the 

 main axis of the shell and three times as long as broad. 



Dimensions. Length of the shell (without spines) 0'2, breadth 0'08. 



Habitat. Central Pacific, Station 265, depth 2900 fathoms ; fossil in the rocks of Barbados. 



2. Spongoprunum atractus, n. sp. 



Shell spindle-shaped, twice as long as broad, with thorny surface. Spongy framework loose, in 

 the whole shell of the same structure, with large meshes, eight to twelve times as broad as the bars. 

 Two polar spines angular, pyramidal, very strong, about one-third as long as the shell, and twice as 

 long as broad. 



Dimensions. Length of the shell 0'2, breadth O'll. 



Habitat. Western Tropical Pacific, Station 225, depth 4475 fathoms. 



3. Spongoprunum amphicylindrus, n. sp. 



Shell nearly cylindrical, four times as long as broad, with rough surface. Spongy framework 

 compact, in the whole shell of equal structure, with small meshes, twice to three times as broad as 

 the bars. Two polar spines cylindrical, very large, longer than the shell, and about one-fourth as 

 thick as its diameter. 



Dimensions. Length of the shell 0'2, breadth 0'05. 



Habitat. South Atlantic, Station 333, surface. 



Subfamily SPONGODRUPPIDA, Haeckel. 



Definition. S pongurida with latticed medullary shell, enclosed by a spoiigy 

 cortical shell. 



Genus 148. Spongodruppa, 1 n. gen. . 



Definition. S pongurida with spongy ellipsoidal cortical shell, enclosing 

 a simple, spherical or ellipsoidal, latticed medullary shell. Polar spines absent. 



The genus Spongodruppa opens the series of Spongodruppida, or of those 

 Spongurida in which the ellipsoidal spongy cortical shell encloses a simple or double, 

 latticed, medullary shell. In Spongodruppa, the simplest and probably the ancestral 

 form of this subfamily, the medullary shell is simple and the polar spines absent. 

 It may be derived from Druppula by a spongy thickening of the simple latticed 

 cortical shell. 



1 Spongodruppa = Spongy olive-fruit ; avoy/o:, 



