REPORT ON THE EADIOLARIA. 571 



3. Pylodiscus cardiopylus, n. sp. 



Cortical shell hexangular, equilateral, five times as broad as the triangular, Tnopy/c-shaped 

 medullary shell. Surface smooth. Three arms triangulai', at the distal end as broad as the 

 three heart-shaped gates. On the margin six strong pyramidal spines in the equatorial plane 

 (adradial, as prolongations of the lateral arm-edges). 



Dimensions. — Diameter of the thsk 015, of the gates 0'05. 



Habitat. — Indian Ocean, Sunda Strait, Eabbe. 



4. Pylodiscus nephropylus, u. sp. 



Cortical shell circular, three times as broad as the circular, I'riopy/c-shaped medullary shell. 

 Surface spiny. Three arms trapezoidal, half as broad as the three kidney-shaped gates. On the 

 margin twelve stronger, conical, radial spmes, opposite in pairs on both sides of the disk, disposed 

 in six pairs at the distal end of the arms. 



Dimensions. — Diameter of the disk 0'2, of the medullary shell 0'06. 



Habitat. — Central Pacific, Station 268, depth 2900 fathoms. 



Subfamily 3. Discopylida, Haeckel. 



Definition. — P y 1 o d i s c i d a witli ^r^ojJ?//e-shaped medullary shell and Pylodiscus- 

 shaped cortical shell, which is surrouuded by a marginal chambered equatorial girdle. 



Genus 251. Discozonium} n. gen. 



Definition. — P ylodiscida with I'/'iop^/^e-shaped medullary shell and Pylodiscus- 

 shaped cortical shell, which is surrounded by an ecj^uatorial chambered girdle. No 

 peculiar osculum on the margin of the disk. 



The genus Discozonium and the following Discojyyie make up together the small 

 group of the Discojiylida, or those Pylodiscida in which a discoidal shell like 

 Pylodiscvs is surrounded by a marginal ec^uatorial girdle ; this girdle is divided into 

 twelve to twenty-four or more chambers by radial beams, which are the external 

 prolongations of the radial marginal spines of Pylodiscus. The latter genus bears 

 therefore to Discozonium the same relation as Sethodiscus in the other D i s c o i d e a 

 does to Lithocyclia, or Phacodiscus to Coccodiscus. 



1. Discozonium cyclonium, n. sp. 



Disk circular, lenticular, with smooth margin, three times as broad as the triangular, Triopyk- 

 shaped medullary shell. Three gates of the cortical shell kidney-shaped, twice as broad as the three 



1 Discozonimn = 'D\sk with girdle ; 3/<rxo.', S^uuiou. 



