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



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1. Stauracontium cruciferum; n. sp. 



Cortical shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the 

 bars ; eight to ten on the quadrant. Eadial proportion of the three spheres = 1:3:9. Connecting 

 radial beams between them six (opposite in pairs in the three dimensive axes), but only four of them 

 are prolonged outside into four stout three-sided prismatic spines, lying in one equatorial plane, as 

 long as the shell diameter. 



Dimensions. Diameter of the outer shell 0'22, middle 0-0*7, inner 0'025 ; cortical pores 0-012, 

 bars 0-003 ; length of the spines 0-2. 



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



2. Stauracontium tetracanthum, Haeckel. 



Haliomma tetracanthum, Ehrenberg, 1872, AbhandL d. k. Akad. d. Wiss. Berlin, p. 295, 

 Taf. x. figs. 7, 8. 



Cortical shell thin walled, smooth, with regular, circular pores, three times as broad as the bars ; 

 five to six on the quadrant. Eadial proportion of the three spheres =1 : 3 : 12. Eadial spines 

 three-sided pyramidal, about as long as the shell diameter. 



Dimensions. Diameter of the outer shell 012, middle 0'03, inner O'Ol ; cortical pores O'Ol, bars 

 0-003 ; length of the spines 01. 



Habitat. Indian Ocean, Zanzibar, depth 2200 fathoms, Pullen. 



3. Stauracontium tetracontium, Haeckel. 



Adinomma tetracanthum, Stohr, 1880, Paleeontogr. 26, p. 91, Taf. ii. fig. 6. 



Cortical shell thin walled, rough, with regular, circular pores, of the same breadth as the bars ; 

 six to seven on the quadrant. Eadial proportion of the three spheres = 1 : 2'5 : 8. Eadial spines 

 three-sided pyramidal, nearly as long as the shell diameter. 



Dimensions. -Diameter of the outer shell 01, middle 0'03, inner 0"013 ; cortical pores and 

 bars 0-006 ; length of the spines 0'08. 



Habitat. Fossil in Tertiary rocks of Sicily ; Grotte, Caltanisetta. 



Subgenus 2. Stauracontellium, Haeckel. 



Definition. Pores of the cortical shell regular, and of nearly equal size and similar 

 form ; surface covered with numerous small thorns or by-spines. 



4. Stauracontium daturceforme, Haeckel. 



Actinomma daturceforme, Stohr, 1880, Palaeontogr. 26, p. 93, Taf. ii. fig. 13. 



Cortical shell thick walled, covered with short thorns, and with regular, hexagonal pores, five times 

 as broad as the bars ; six to seven on the quadrant. Eadial proportion of the three spheres = 

 1:3: 3'5. Eadial spines six-sided pyramidal, about half as long as the radius and one-fourth as 

 broad. 



