752 THE VOYAGE OF H.M.S. CHALLENGER. 



11. Acanthoma cuspidata, Haeckel. 



Acanthomdra cnsjridafa, Haeckel, 1862, Monogr. d. KadioL, p. 3S3, Taf. xviii. fig. 11. 



Spines quadrangular jDyramidal, with four prominent lamellar edges, tapering gradually from the 

 broad base towards the simple distal apex. Basal leaf-cross twice as broad, with a small central 

 pyramid. 



Dimensions.— Length of the spines O'o, basal breadth 0-012 ; leaf-cross 0-025. 



Halntat. — Cosmojiohtan ; MecUterranean, Atlantic, Pacific, surface. 



12. Acanthonia quailrifolia, Haeckel. 



Acanthuiiidra quarlrifilia, Haeckel, 1862, Ifonogr. d. EaJiol., p. 382, Taf. xviii. fig. 10. 



Spines in the basal part quadrangular pyramidal, with four prominent lamellar edges and a large 

 basal leaf-cross ; in the distal part three to six times as long, cylindrical, of equal breadth. Apex 

 simple, conical, or bifid. Central capsule yellow or whitish. This common species differs 

 from the nearly allied Ardnthometron catcrvatum mainly Ijy the strong development of the 

 large basal leaves or wings. 



Dimensions. — Length of the spines Oo to 0'5, breadth in the distal half 0'002, in the basal 

 part 0-02. 



Habitat. — Mediterranean ; North Atlantic, Stations 252 to 254 ; Fsei'oe Channel, Gulf Stream, in 

 enormous numbers, John IMurray, surface and at various depths.- 



13. Acanthonia diplopyraini.^, n. sp. 



Spines formed like a quadrangular double pyramid or an irregular octahedron ; the basal leaf- 

 cross being extremely developed, with four very large and thin lamellar leaves ; the basal halves of 

 the twenty double pyramids are united by the meeting edges of those leaves, while their distal 

 halves are free, with simple apices. Therefore the four triangular leaves of each spine are equally 

 thinned from the middle towards the two ends. 



Dimensions. — Length of the spines O'l to 0"2, greatest breadth OO-l to O'OS. 



Habitat. — Central Pacific, Stations 266 to 274, surface. 



14. Acanthonia midtispina, Haeckel. 



Acanthomdra mnltispina, J. Miiller, 1858, AbLaiidl. d. k. Akad. d. Wiss. Berhn, p. 47, Taf. vii. 



figs. 6-9. 

 Acanthomdra multispina, Haeckel, 1862, Monogr. d. Eadiol., p. 384. 



Spines quadrangular, with four lamellar jirominent edges, iir the proximal half nearly prismatic, 

 in the distal half jjyramidal ; both halves separated by a prominent short tooth on each edge. Here 

 in the middle part the breadth (including the four teeth) is equ;il to the basal leaf-cross. Central 

 capsule opaque, brown. 



Dimensions. — Length of the spines 0'2 to 0'3, greatest breadth O'Ol to 0'02. 



Hahitat. — Mediterranean (Messina) ; Tropical Atlantic, Station 348. 



