REPORT ON THE RADIOLARIA. 01 



2. Spongodictyon cavernosum, n. sp. 



Spongy framework of the cortical shell rather compact in the inner part, which immediately 

 envelops the double meduUary sheU ; very loose, with large caverns in tlie outer part, caverns of 

 the surface larger than the meduUary shell. Both meduUary sheUs with regular circular pores, 

 three times as broad as the bars. 



Dimensions. — Diameter of the cortical sheU O'S to 04, outer meduUary shell 01, inner Q-Q'S. 



Habitat. — Tropical Atlantic, Station 338, surface. 



Subgenus 2. Spongodictyoma, Haeckel. 



Definition. — Spongy cortical shell on tlie inner surface with a smooth lattice-pIatc 

 (or third medullary shell), which is connected by radial beams with the inner double 

 medullary shell. 



3. Spongodictyon trigonizon, Haeckel. 



Spongodictyon trigonizon, Haeckel, 1862, Monogr. d. Eadiol., p. 4.59, Taf. xxvi. figs. 4-6. 

 Dictyosoma tj-igonizon, Haeckel, 1860, jMonatsber. d, k. preuss. Akad. d. "Wiss. Berlin, p. 841. 



Spongy framework of the cortical sheU very loose, with very large, for the most part triangular 

 meshes, which are two to six times as large as the enclosed double meduUary sheU. From 

 the surface of the latter arise numerous radial beams, which are connected by a spherical lattice- 

 plate, forming the smooth inner surface of the spongy sphere (or a tliird medullary sheU). The 

 structure of the framework reminds one of the Ph.eodaeium Smjcna (PL 108). Pores of both 

 meduUary sheUs regular circular, twice as broad as the bars. 



Dimensions. — ^Diameter of the cortical sheU 0'5 to I'lo, outer meduUary 0"05, inner 0"035. 



Hahitat. — Mediterranean, Messina, surface. 



4. Spongodictyon arcadophoron , u. sp. 



Spongy framework of the cortical sheU in the inner part very loose, in the outer part more 

 compact ; outer meshes scarcely as large as the inner meduUary sheU (or only half as large), inner 

 meshes two to four times as large. From the surface of the double meduUary sheU arise 

 numerous radial beams, which are forked at equal distances from the centre ; the fork branches 

 are curved and united together by dichotomous branches, like elegant arcades ; and these arcades 

 form together the large polygonal meshes on the inside of the cortical sheU (or a thhd meduUary 

 shell). Both medullary shells with regular circular pores, of the same breadth as the bars. 



Dimensions. — Diameter of the cortical .shell 0'2, outer medullary shell 0'04, inner 0'02. 



Habitat. — Tropical Atlantic, Station 349, surface. 



