REPORT ON THE RADIOLARIA. 745 



10. Acanthometron catervatum, Haeckel. 



Acanthometra brevispina, Haeckel, 1862, Monogr. d. Radiol., p. 382, Taf. xv. fig. 5, Taf. xviii. 

 fig. 9. 



Spines cylindrical, nearly of equal breadth throughout their whole length. Apex either simple, 

 conical, or bifid. Base with a large leaf-cross, four to six times as broad as the spine itself. Central 

 capsule transparent, yellow. The Atlantic specimens have much longer spines than those figured 

 from the Mediterranean, but are otherwise not different. Therefore I have changed the inconvenient 

 name brevispinum into catervatum. 



Dimensions. Length of the spines Ol to - 3, breadth 0005 to O'OOS ; basal leaf-cross 0'02 to 

 0-032. 



Habitat. Mediterranean (Messina) ; North Atlantic, Station 354, Gulf Stream (Fseroe Channel) 

 in great abundance, John Murray, surface. 



Subgenus 3. Astrolithium, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. 



Wiss. Berlin, p. 810. 



Definition. Spines in the basal part grown perfectly together, so that the whole 

 skeleton forms a single piece of acanthin ; a star with twenty equal rays. 



11. Acanthometron bulbiferum, n. sp. (PL 130. fig. 1). 



Astrolithium bulbiferum, Haeckel, 1881, Prodromus, p. 466. 



Spines needle-shaped, cylindrical, very thin and long, with simple apex ; suddenly thickened 

 and forming a broad regular cone at the central base ; all twenty conical bulbs have their 

 broad bases grown together and forming a central icosahedron of acanthin ; from its twenty faces 

 arise the circular bases of the cones in regular disposition. 



Dimensions. Length of the spines 0'2 to 0'5, breadth O'OOl to 0'003 ; height of the basal 

 cones 0'06, basal breadth of them 0'02. 



Habitat. Central Pacific, Stations 265 to 274, surface. 



12. Acanthometron bifidum, Haeckel. 



Astrolithium bifidum., Haeckel, 1862, Monogr. d. Radiol., p. 400, Taf. xx. fig. 5. 



Spines needle-shaped, cylindrical, of equal breadth in their whole length. Distal apex 

 bifid, with two parallel straight teeth. Central bases of all twenty spines grown perfectly 

 together and forming a central sphere of acanthin. Central capsule brown opaque. 



Dimensions. Length of the spines 0'2, breadth 0'003. 



Habitat. Mediterranean (Messina), Haeckel, surface. 



(ZOOL. CHALL. EXP. PART XL. 1885.) Rr 94 



