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



11. Acanthonia cuspidata, Haeckel. 



Acanthometra cuspidata, Haeckel, 1862, Monogr. d. Radiol., p. 383, Taf. xviii. fig. 11. 



Spines quadrangular pyramidal, 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 0'5, basal breadth 0'012 ; leaf-cross 0'025. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Pacific, surface. 



12. Acanthonia quadrifolia, Haeckel. 



Acanthometra quadrifolia, Haeckel, 1862, Monogr. d. Radiol., 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 Acanthometron catervatum mainly by the strong development of the 

 large basal leaves or wings. 



Dimensions. Length of the spines 0'3 to 0'5, breadth in the distal half O002, in the basal 

 part 0-02. 



Habitat. Mediterranean ; North Atlantic, Stations 252 to 254 ; Faeroe Channel, Gulf Stream, in 

 enormous numbers, John Murray, surface and at various depths. 



13. Acanthonia diplopyramis, 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 0'04 to 0'08. 



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



14. Acanthonia multispina, Haeckel. 



Acanthometra multispina, J. Miiller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 47, Taf. vii. 



figs. 6-9. 

 Acanthometra multispina, Haeckel, 1862, Monogr. d. Radiol., p. 384. 



Spines quadrangular, with four lamellar prominent edges, in the proximal half nearly prismatic, 

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

 in the middle part the breadth (including the four teeth) is equal 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. 



Habitat. Mediterranean (Messina) ; Tropical Atlantic, Station 348. 



