REPORT ON THE RADIOLARIA. 1077 



15. Dictyospyris hexastoma, n. sp. 



Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores small, irregular, roundish. 

 Three pairs of larger pores on each side of the ring. Basal plate with six large pores; the middle 

 pair (cardinal) twice as large as the anterior (jugular) and the posterior (cervical). 



Dimensions. Shell - 08 long, 012 broad. 



Habitat. Fossil in Barbados. 



16. Dictyospyris enneastoma, n. sp. 



Shell ellipsoidal, smooth, without external sagittal stricture, but with an internal free sagittal 

 ring. Pores small and numerous, regular, circular. No larger annular pores. Basal plate with 

 nine pores, three larger interradial alternating with three pairs of adradial. 



Dimensions. Shell 0'07 long, Oil broad. 



Habitat. South Pacific, Station 297, depth 1775 fathoms. 



17. Dictyospyris polystoma, n, sp. 



Shell nut-shaped, mammillate, with distinct sagittal stricture. Pores small and numerous, 

 irregular, on each side of the ring three to five times as large as on the lateral sides. Basal plate 

 with twelve large pores (four central and four alternate pairs of peripheral). 



Dimensions. Shell 01 long, 014 broad. 



Habitat. Tropical Atlantic, Station 338, depth 1990 fathoms. 



Family LIII. THOLOSPYRIDA, n. fam. 

 (PL 87, figs. 7-10 ; PI. 89, figs. 1-4 ; PL 95, figs. 14-16). 



Definition. S pyroidea with a galea, but without thorax ; the shell being 

 composed of the bilocular cephalis and of an aboral cupola or galea arising from its 

 coryphal face. 



The family Tholospyrida differs from the preceding Zygospyrida, its ancestral 

 group, in the development of a galea, i.e., a fenestrated hemispherical or dome-shaped 

 cupola, which covers the upper face of the cephalis like a cap. 



Only three species of this family have been hitherto described : Pylospyris (or 

 Spyridobotrys) trinacria, figured in my Monograph (1862), Pylospyris (or Lithopera) 

 denticulata, figured by Ehrenberg (1872), and Lophospyris (or Ceratospyris) acuminata, 

 figured by Hertwig (1879). Fourteen new species have been found in the collection 

 of the Challenger, which we dispose here among five genera. These may be derived 

 from corresponding genera of Zygospyrida by the development of a galea. 



