REPORT ON THE RAUIOLARIA. 449 



15. Heliodiscus humboldti, Haeckel. 



Heliodiscus humboldti, Haeckel, 1862, Monogr. d. Radiol., p. 438. 



Haliomma humboldti, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 27; Abhandl. d. k. Akad. 



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

 Haliomma humboldti, Bury, 1862, Polycystins of Barbados, pi. viii. rig. 3 (at left). 



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

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

 proximal half radially striped, on the margin with sixteen to twenty short, flat, triangular teeth, 

 which are longer than the breadth of the girdle. 



Dimensions. Diameter of the disk 012 to O2, of the medullary shell 0'03 to 0'05 ; length of 

 the marginal spines 0'02 to 0'04, basal breadth 002. 



Habitat. Fossil in Barbados (common and very variable). 



16. Heliodiscus maryinatus, n. sp. (PI. 34, fig. 9). 



Disk with smooth surface, three times as broad as the medullary shell. 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 with twelve to eighteen very short and broad, 

 triangular, marginal spines. 



Dimensions. Diameter of the disk 015 to 0'2, of the medullary shell - 05 to 0'06 ; length of 

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



Habitat. Central Pacific, Stations 265 to 268, depth 2900 fathoms. 



17. Heliodiscus sidcatus, 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 the 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 Heliodismis ylypkodon, 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 0'05 to 0'06, basal breadth 0'04 to 0'05. 



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



18. Heliodiscus unibonatus, Haeckel. 



Haliomma umbonatum, Ekrenbei'g, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, 

 Taf. xxvii. fig. 4. 



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

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

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

 variable in size and disposition. 



(ZOOL. CHALL. KXP. PART XL. 1885.) Rf 57 



