256 THE VOYAGE OF H.M.S. CHALLENGER. 



protuberances of the outer medullary shell, and connect it with the cortical shell. Outer prolonga- 

 tions of these form the bristle-shaped spines of the surface. 



Dimensions. Diameter of the outer shell 0'22, middle 0'09, inner 0'04 ; cortical pores O'Ol to 

 0'02, bars O'OOl to O002 ; length of the radial spines 0'2. 



Habitat. Central Pacific, Station 266, surface. 



14. Actinomma schwageri, Stohr. 



Actinomma sclncageri, Stohr, 1880, Paleeontogr., vol. xxvi p. 92, Taf. ii. fig. 9, l>. 



Cortical shell thick walled, with irregular, large, polygonal meshes, five to twelve times as broad 

 as the bars ; six to eight on the radius. Both medullary shells with very small, circular, regular 

 pores. Radial proportion of the three spheres = 1:2:9; connecting radial beams between them 

 nine, prolonged outside into nine short stout, three-sided pyramidal spines, as long as the diameter 

 of the inner shell. 



Dimensions. Diameter of the outer shell O'l?, middle 0'04, inner 002 ; cortical pores O'Ol to 

 0'03, bars 0'006 and less ; length of the spines 0'02, basal breadth O'Ol. 



Habitat. Fossil in Tertiary rocks of Sicily, Grotte, Stohr. 



15. Actinomma dodecomma, n. sp. 



Cortical shell thin walled, with irregular, roundish pores, three to six times as broad as the bars. 

 Both medullary shells with regular, circular pores, twice as broad as the bars. Eadial proportion of 

 the three shells = 1:2-5:7; connecting radial beams between them twelve, regularly disposed, pro- 

 longed outside into twelve strong, three-sided pyramidal spines, as long as the radius. 



Dimensions. Diameter of the outer shell 014, middle 0'05, inner 0'02 ; cortical pores O'OOS to 

 0-018, bars 0'003 ; length of the spines 0'08, breadth 0'02. 



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



16. Actinomma pachycapsa, n. sp. 



Cortical shell very thick walled, with irregular, roundish pores, twice to four times as broad as 

 the bars ; twelve to sixteen on the radius. Eadial proportion of the three spheres =1:3:12. Both 

 medullary shells of similar irregular structure, connected with the cortical shell by twelve regularly 

 disposed radial beams, which are prolonged outside into twelve short stout conical spines, as long 

 as the diameter of the middle shell. 



Dimensions. Diameter of the outer shell 0'25, middle 0'06, inner 4 02 ; cortical pores 0'006 to 

 0-012, bars 0'003 ; length of the spines 0'05, breadth 0'02. 



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



17. Actinomma giganteum, n. sp. 



Cortical shell thick walled, little larger than the outer medullary shell, whilst the inner is only 

 one-tenth as large. Pores of all three shells irregular, roundish, or subcircular, twice to three tunes 



