REPORT ON THE RADIOLARIA. 359 



2. Cannartus bitubulus, n. sp. 



Pores of the shell regular, circular, hexagonally framed, of the same breadth as the bars ; 

 fourteen to sixteen on the half meridian, ten to twelve on the half equator. Polar tubes cylindrical, 

 longer than the main axis, sulcated, distal ends broken off. (Similar to Pipetta tuba, PI. 39, 

 fig. 7, but with equatorial stricture and without medullary shell.) 



Dimensions. Main axis 016, equatorial axis 0'12 ; meshes and bars 0'006 ; length of the 

 polar tubes 0-2, breadth 0'025. 



Habitat. South Atlantic, Station 332, depth 2200 fathoms. 



3. Cannartus biscottus, n. sp. 



Pores of the shell irregular, roundish, twice to three times as broad as the bars ; ten to twelve 

 on the half meridian, six to eight on the half equator. Polar tubes conical, shorter than the 

 main axis, with closed apex. (Similar to Cannartidium bicinctum, PI. 39, fig. 18, but without 

 enclosed medullary shell.) 



Dimensions. Main axis Oil, equatorial axis 0'07 ; meshes 0'005 to - 01, bars 0'003 ; length of 

 the polar tubes 0'08, breadth on the base 0'03. 



Habitat. Equatorial Atlantic, Station 348, depth 2450 fathoms. 



Family XV. C Y p H I N i D A, Haeckel (PL 39, figs. 1 1-19). 

 Cyphinida, Haeckel, 1881, Prodromus, p. 462. 



Definition. Prunoidea with ellipsoidal twin-shell, divided by an equatorial 

 stricture into two communicating hemiellipsoidal or hemispherical chambers ; this 

 external twin-shell (cortical shell) is either simple or double, and encloses one or more 

 internal concentric shells (medullary shells). Central capsule ellipsoidal, commonly 

 with an equatorial constriction. 



The family Cyphinida have the same characteristic twin-form of the cortical shell 

 as the Artiscida, but differ from them in the presence of a simple or double internal 

 medullary shell, connected with the cortical shell by radial beams. The fenestrated shell 

 is therefore composed of two or more concentric shells as in the Druppulida, but differs 

 from these in the ring-like equatorial constriction. 



Hie Medullary Shell, in the middle of the central capsule, is either single or double, 

 composed of two concentric shells. As in the Druppulida, the form of the medullary 

 shells is either spherical (PI. 39, fig. 12a) or lenticular, compressed from both poles of 

 the main axis (PL 39, fig. 18a) ; sometimes the inner medullary shell is spherical, the 

 outer lenticular. 



The Radial Beams, which connect the medullary shell with the equatorial constriction 

 of the cortical shell, lie either all in the equatorial plane (PL 39, fig. 11) or near it on 

 both sides (PL 39, figs. 12, 18a). 



