REPORT ON THE RADIOLARIA. 295 



surface spiny; between every three meshes arises a strong radial spine, twice to three times as long 

 as the diameter of the meshes ; the base of tlie spine is like a three-sided pyramid. 



Dimensions. — Major axis of the ellipsoid 012, minor axis 0'08; meshes 0'006, bars 0'005. 



Habitat. — Central area of the Pacific, Station 268, depth 2900 fathoms. 



4. Ellipsidium opimtia, n. sp. 



Proportion of the longer axis to the shorter = 5 :4. Shell thin walled, with irregular, roundish 

 meshes of different size and form, about twice to three times as broad as the irregular, thin bars 

 between them ; ten to fifteen meshes on the half equator. Between the meshes arise numerous 

 thin, bristle-like, radial spines, about as long as the shorter radius of the shell. The number of the 

 meshes may be three to four times as gi'cat as the number of the spines. 



Dimensions. — Major axis of the ellipsoid 0'15, minor axis 012; pores 0'006 to O'Ol, bars 0003 

 to 0'004 



Habitat. — Southern Pacific, Station 284, surface. 



5. EUipsidium echiniditnn, n. sp. 



Proportion of the longer axis to the shorter =^4:3. Shell thick walled, with irregular, roundish 

 pores of different size and form, about as large or somewhat smaller than the l;>road bars ; twelve to 

 sixteen pores on the half equator. On the surface, irregularly scattered, twenty to thirty strong, 

 three-sided pyramidal, radial spines, one-fourth to one-half as long as the main axis. 



Dimensions. — Major axis of the ellipsoid 016, minor 012 ; pores and bars 0"002 to O'OOS ; 

 length of the radial spines 0^04 to 0'08, basal breadth 001. 



Habitat. — Equatorial Atlantic, Station 347, depth 2250 fathoms. 



Genus 125. EUipsoxtjyJius,^ Dunikowski, 1882, Denksclir. d. k. Akad. d. 



Wiss. AVieu, vol. xlv. p. 25. 



Definition. — Ellipsida with simple ellipsoidal shell, the main axis of which is 

 prolonged at both poles into two strong opposite spines of equal size and similar form. 



The genus Ellipsoxiphus w^as established by Dunikowski (in 1882, loc. cit.) for those 

 simple amphistylous fenestrated shells, formerly united with Xiphosp]i(Bra, in which the 

 mathematical form of the shell itself is not a true sphere, but an ellipsoid. It may 

 therefore be derived from Xip>hosphcera by prolongation of the axis in which lie both 

 polar spines ; but it may also be derived from Cenellipsis by the production of two 

 equal spines at the poles of the main axis. 



* Elli'psoxiphus='E[\\\}&o\A with swords ; iXhu'^^ii, J/ipoj. 



