REPORT ON THE RADIOLARIA. 453 



{commonly between ten and twenty) is also here varialile in one and the same 

 species. The greater number of observed species of Astro2jhacus resemble in a very 

 remarkable manner the corresponding species of Hdiodisms, and differ only in the 

 double medullary shell. 



Subgenus 1. Asfrophaeetfa, Haeekel. 



Dejinition. — Surface uf the disk smooth, without radial spines. Bases of the 

 marginal spines free, without a connecting equatorial girdle. 



1. Astrojyhacus asteriscus, n. sp. 



Disk with smooth surface, three times as broad as tlie outer and eight times as Ijroad as the inner 

 medullary shell. Pores regular, circular ; twelve to fourteen on the radius. Marginal spines 

 fifteen to twenty, of variable size and disposition ; the largest as long as the radius of the disk, as 

 broad at the base as one pore. (Very similar to HcUodiscus nsferiscus, VI. 33, fig. S, but differing 

 in the double medullary shell.) 



Dimensions. — Diameter of the disk O'l*, of the outer medullary shell 0-u7, of the inner 0'025 ; 

 length of the marginal .spines 0'05 to O'l, basal breadth O'Ol. 



ffcdiifaf.— Central Pacific, Station 2G.i, depth 2900 fathoms. 



2. A.'itrophacus troch'tscus, n. sp. (PI. 34, lig. 14). 



Disk with smooth surface, three times as broad as the outer and seven times as broad as the 

 inner meduUary shell. Pores irregular, roundish ; twelve to thhteeu on tlie radius. Marginal spines 

 sixteen to twenty, conical, of irregular variable size and disposition ; the largest as long as the 

 iiuier medullary shell. (Differs from Heliodiscus trocJiisciis in the ilouble medullary shell.) 



Bimensions. — Diameter of the disk 0'22, of the outer medullary shell O'OS, of the inner O'Oo. 



Habitat. — North Atlantic, Station 354, surface. 



3. Astrophacus Solaris, n. .sp. (PL 32, fig. l). 



Disk with smooth surface, three times as broad as the outer and seven times as liroad as 

 the inner medullary sliell. Pores subregular, roundish ; twelve to fourteen on the radius. 

 Marginal spines one Imndred to one hundred and twenty, conical, flexuose, of irregular size and 

 form ; the largest one-third as long as the diameter of the disk. The spines he not only in the 

 equatorial plane (as is usual) but also in two to four crowded girdles on both sides of it. (Very 

 similar to Hdiodisms solaster, PI. 34, fig. 4, but of double the .size, with double the number of 

 spines and witli a double medullary shell.) 



Dimensions.-— Vymmat&x of the disk 0'3, of the outer medullary shell O'll, of the inner 0'04.'"i; 

 length of the spines 0-03 to 0-1, basal breadth Q-Ol to 0-02. 



Habitat. — Indian Ocean, Sunda Strait, Pabbe, surface. 



i) 



