REPORT ON THE RADIOLARIA. 



pores O'OOS, bars 0'004. Length of the polar tubes 0'07, basal breadth 0'04 ; pores 0-003, 

 bars 0-002. 



Habitat. North Pacific, Station 253, depth 3125 fathoms. 



2. Cannartiscus amphicylindrus. n. sp. 



Cortical shell thick walled, rough, with subregular, circular pores, twice to four times as broad 

 as the bars ; six to seven on the half meridian, ten to twelve on the half equator of each 

 chamber. Polar tubes cylindrical, on the distal end open (broken off?) nearly as long as. 

 the main axis, somewhat narrower than the spherical medullary shell. Pores of the tubes much 

 smaller than those of the chambers. 



Dimensions. Main axis (without tubes) 017, greatest breadth 0'12 ; pores 0'006 to 0'012, 

 liars 0-003. Length of the polar tubes 015, breadth of them 0'03 ; pores 0'003, bars 0'002. 



Habitat. Pacific, central area, Station 268, 2900 fathoms ; the same form occurs fossil in the 

 rocks of Barbados. 



Genus 162. Cannartidium, 1 n. gen. 



Definition. C y p h i n i cl a with simple cortical shell and double medullary shell, 

 with two hollow fenestrated polar tubes, opposite on both poles of the main axis. 



The genus Cannartidium differs from Cannartiscus and Cannartus in the duplica- 

 tion of the medullary shell, which is composed of two concentric spheres or compressed 

 lenticular spheroids. The three genera named form therefore one morphological series, 

 with identical cortical shell, and only differing in the absence or presence of a simple or 

 double medullary shell. 



Subgenus 1. Cannartidella, Haeckel. 



Definition. Surface of the cortical shell smooth or a little rough, but without spines 

 <>r fenestrated protuberances. 



1. Cannartidium ampliiconicum, n, sp. 



Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars ; 

 eight to nine on the half meridian, fifteen to sixteen on the half equator of each chamber. Polar 

 tubes conical, with smaller pores, tapering towards the closed apex, about as long as one single 

 chamber, at the base one-third as broad as the equatorial constriction. Both concentric medul- 

 lary shells spherical. (Nearly identical with Cannartiscus amjihiconiscus, PI. 39, fig. 19, but differs 

 in the possession of the double medullary shell.) 



1 Cannartidium = Small loaf with tubules; xaava, li 



