REPORT ON THE RADIOLARIA. 44i> 



15. Heliodif^cus humhohUi, Haeckel. 



Heliodisciis liumholdti, Haeckel, 1862, Monogr. d. Eadiol., p. 438. 



Halinmma ImmhohUi, Ehrenberg, 1854, JNIikrogeol., Taf. xxxvi. fig. 27; Abliandl. d. k. Akad. 



d. Wiss. Lerlin, 1875, Taf. xxvii. fig. 3. 

 Haliomma humhohlti, Buiy, 1862, Polycystins of Barbados, pi. viii. fig. 3 (at left). 



Disk with smooth surface, four times as broad as tlie medullary shell. Pores regular, circular ; 

 eighteen to twenty on the radius. Equatorial girdle half as broad as the medullary shell, in the 

 ])roximal half radially striped, on the margin with sixteen to twenty short, Hat, triangular teeth, 

 which are longer than tlie lireadth of the girdle. 



Dimensions. — Diameter of the disk 012 to 0-2, of the medullary shell 0-0?> to O'O.t ; length of 

 the marginal spines 0'02 to 0'04, basal breadth 0-02. 



Hahitat. — Fossil in Barbados (common and very variable). 



IG. Ileliodiscus marginatus, n. sp. (PI. 34, fig. 9). 



Disk witli smooth surface, three times as broad as the medullary sliell. Pores regular, circular ; 

 nine to ten on the radius. Equatorial girdle one-fourth to one-half as broad as the medullary shell, 

 in the whole breadth radially striped, on the margin witli twelve to eighteen very short and broad, 

 triangular, marginal spines. 



Dimensions. — Diameter of the disk 015 to 0-2, of the medullary shell O'Oo to O'OG ; length of 

 the marginal spines O'Ol to 0'02, basal breadth 0'02. 



Habitat. — Central Pacific, Stations 265 to 268, depth 2900 fatlioms. 



17. IFcI iodise us snlcatu.^, n. sp. 



Disk with smooth surface, four times as broad as the medullary shell. Pores subregular, 

 circular ; twelve to fifteen on the radius. Equatorial girdle as broad as tlie medullary .shell, in the 

 whole breadth radially striped, on the margin with ten to fifteen triangular, deeply sulcated teeth, 

 about as long and broad as the medullary shell. (Similar to Hdiodiscus glyphodon, PI. 35, fig. 2, but 

 with broad sulcated girdle and shorter, more numerous spines.) 



Dimensions. — Diameter of the disk 015 to 0'2, of the medullary shell 0'04 to 0-05 ; length of 

 the radial spines O'Oo to 0-06, basal breadth 0-04 to O'Oo. 



Habitat. — Atlantic and Pacific, tropical part, many Stations, surface. 



18. Heliodiscus umhonutus, Haeckel. 



Haliomma umhonafiiin, Ehrenberg, 1875, AbhauJl. d. k. Akad. d. "Wiss. Berlin, p. 74, 

 Taf. xxvii. fig. 4. 



Disk with smooth surface, three times as liroad as the medullary shell. Pores irregular, 

 roundish ; eight to ten on the radius. Equatofial girdle half as Ijroad as the medullary shell, hyaline, 

 not radially striped, on the margin witli ten to twenty triangular, irregular, smooth teeth, very 

 variable in size and disposition. 



(ZOOL. CHALL. EXP. PART XL. 1885.) Rr 57 



