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



Subgenus 2. Thecosphcerella, Haeckel. 



Definition. Pores of the cortical shell regular, circular, without hexagonal frames 

 or lobes, all of nearly equal size and form. 



5. Thecosphcera inermis, Haeckel. 



Actinomma inerme, Haeckel, 1862, Monogr. d. Eadiol., p. 440, Taf. xxiv. fig. 5. 

 Haliomma inerme, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 815. 



Cortical shell thin walled, rough, with regular circular pores, twice as broad as the bars. Eadial 

 proportion of the three spheres and of their circular regular pores = 1:2:4. All three spheres 

 connected by twelve regularly disposed radial beams. 



Dimensions. Diameter of the outer shell 01, middle O05, inner O025 ; cortical pores O'OOG, 

 bars 0-003. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific, at many Stations and at 

 various depths. 



6. Thecosphcera cequorea, Haeckel. 



Haliomma cequorea, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83; 



Mikrogeol., 1854, Taf. xxii. fig. 35. 

 Actinomma cequorea, Haeckel, 1862, Monogr. d. Eadiol., p. 443. 



Cortical shell thick walled, smooth, with regular circular pores of the same breadth as the bars. 

 Eadial proportion of the three spheres and of their regular pores = 1:2:6 or =1:3:9; they are 

 connected by six radial beams, opposite by pairs in the three dimensive axes. 



Dimensions. Diameter of the outer shell 0'08 to 012, middle 0'03 to 0'04, inner 0'09 to 012; 

 cortical pores and bars about O'OOG. 



Habitat. Mediterranean, Corfu, surface ; fossil in Greece and Sicily. 



7. Thecosphcera medusa, Haeckel. 



Haliomma medusa, Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 130; Mikrogeol., 



1854, Taf. xxii. figs. 33, 34. 



Actinomma medusa, Haeckel, 1862, Monogr. d. Kadiol., p. 444. 

 Actinomma medusa, Stohr, 1880, Palaeontogr., Bd. xxvi. p. 90, Taf. ii. fig. 3. 



Cortical shell thick walled, rough or thorny, with regular circular pores of the same breadth as 

 the bars. Eadial proportion of the three spheres = 1 : 2 : 4 (or 1 : 2, 5 : 6) ; they are connected by 

 four radial beams, crossed by pairs in two diameters, perpendicular one to another. 



Dimensions. Diameter of the outer shell 0'08 to 012, middle 0'04 to O'OG, inner 0'02 to 0'025; 

 cortical pores and bars in average 0'005. 



Habitat. Fossil in Tertiary rocks of Barbados and the Mediterranean. 



