REPORT ON THE RADIOLARIA. 95 



Genus 29. CoUosphaan,^ J. Mtiller, 1855. 



Definition. — C o 1 1 o s p li 8e r i d a with simple shells, smooth on the inside and on 

 the outside, without any spines or tubuli. 



The genus CoUos])hcBra is the most simple form of all CoUosphserida, and must be 

 regarded as the common ancestral form of this family. As the lattice-shell is quite a 

 simple sphere, without any spines, tubules, or other peculiar productions, it agrees 

 perfectly with CenosphcBra, and represents the social or polyzoid aggregate of this 

 solitary or monozoid genus. Therefore a certain distinction between the isolated shells 

 of the two genera is often very difficult or even impossible ; but commonly this distinction 

 is possible owing to the circumstance, that in the majority of the CoHosphcerce the shell 

 is more or less u-regular roundish or j)olyhedral, not quite spherical, as in Cenosphcera. 



Subgenus 1. EucollosplicBra, Haeckel. 

 Definition. — Shell a regular or subregular sphere. 



1. Collosphcera p)rimordialis, n. sp. 



Shell a regular sphere, with very delicate and regular network of hexagonal meshes. Six to 

 eight meshes in the half meridian of the shell. Diameter of the meshes ten to fifteen times as 

 broad as the thin bars between them. Can be regarded as social form of Cenosphwra primordialis. 



Dimensions. — Diameter of the shell 01 to 012, of the pores O^OOS. 



HaMtat. — Central Pacific, Stations 271 to 2*74, surface. 



2. Collosphcera regularis, n. sp. 



Shell a regular sphere, with a perfectly regular network of circular meshes, all of the same size. 

 Ten to twelve meshes in the half meridian of the shell. Diameter of the meshes the same as 

 that of the bars between them. 



Dimensions. — Diameter of the shell 01 to 012, of the pores O'OOS to 0'006. 



Habitat. — Indian Ocean, Madagascar, surface, Eabbe. 



3. Collosphcera globularis, n. sp. 



Shell a regular sphere, with subregular network of circular meshes of different sizes ; few large 

 pores between many smaller pores. Ten to twenty meshes in the half meridian of the shell. 

 Diameter of the meshes from half to twice as broad as that of the bars. 



^ CoHo6y/tcEra=Jelly-sphere ; xixhtt., a'Pal^ct. 



