2.j8 the voyage of h.m.s. challenger. 



3. Echinomma aculeatum, Haeckel. 



Acfhwmma aculeatum, Stolir, 1880, Palseontogr., vol. xxvi. p. 92, Taf. ii. fig. IL 



Cortical shell thick waUed, with regular, circular pores, of the same hreadth as the bars ; eight to 

 ten on the radius. Eadial proportion of the three spheres = 1:2:8. Surface covered with short 

 conical by-spines ; about twenty strong main spines, three-sided pyramidal, one-third as long as 

 the shell diameter. 



Dimensions. — Diameter of the outer shell 016, middle 0'04, inner 0'02 ; cortical pores and bars 

 0'003 ; length of the main spines 0'05, basal breadth O'Olo. 



Habitat. — Fossil in the Tertiary rocks of Sicily and Barbados ; living in tlie Atlantic, Station 

 332, depth 2200 fathoms. 



4. Echinomma diadema, n. sp. 



Cortical sliell thick walled, with regular, circular pores, twice as broad as the bars ; sixteen to 

 eighteen on the radius. Eadial proportion of the three spheres .-=1 :3 : 11. Surface covered with 

 short bristle-shaped by-spines, one-third as long as the twelve stout conical main spines, which 

 reach in length the radius, and lie opposite in pairs in six axes. 



Dimensions. — Diameter of the outer shell 022, middle 0-06, inner 0'02 ; cortical pores 0006, 

 bars 0"003 ; length of the main spines 012, basal breadth 0'02. 



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



Subgenus 2. Eckinommvra, Haeckel. 

 Definition. — Pores of the cortical shell irregular, of different size or form. 



5. Echinomma sphcerechinvs, n. sp. (PI. 29, fig. 2). 



Aettnomma sphcerecMnus, Haeckel, 1879, Atlas (pi. xxix. fig. 2). 



Cortical shell thin walled, with irregular, roundish pores, twice to five times as broad as the bars ; 

 Kve to seven on the radius. Both medullary shells with regular, circular pores, twice as broad as 

 the bars. Piadial proportion of the three spheres = 1:2:4. Surface covered with thirty to fifty 

 pyramidal main spines, as long as the diameter of the inner shell, and with numerous small conical 

 l)y-spines of half the length. 



Dimensions. — Diameter of the outer shell Oil, middle O'Oo, inner 0-025 ; cortical pores 0-01 to 

 0-02, bars 0-004 ; length of the main spines O'OS, basal breadth 0005. 



Habitat. — North Atlantic, Station 353, surface. 



G. Echinomma trinacrium,, Haeckel. 



Actinonima trinacrium, Haeckel, 1862, Monogr. d. Eadiol., p. 441, Taf. xxiv. figs. 6-8. 



Cortical shell thin walled, with irregular, roundish pores, twice to three times as broad as the 

 bars. Both medullary shells with regular, circular pores. Eadial proportion of the three spheres 



