REPORT ON THE RADIOL ARIA. 751 



gular pyramid, without leaf-cross. All the twenty spines of this species exhibit nearly the same form, 

 which is seen in the frontal or anterior (hydrotomical) spine of Amphilonche anomala (Monogr. d. 

 Eadiol, Taf. xviii. fig. 23, a). 



Dimensions. — Length of the spines 0'15, breadth in the middle part 0'012, on both ends 0'02.5. 



Habitat. — South Pacific, Station 288, surface. 



8. Acanthoma quadrangula, n. sp. 



Spines quadrangular prismatic, with smootli prominent straight edges, but of very different 

 breadth in both halves ; the iinier or proximal half (inside the central capsule) twice to four times 

 as broad as tiie outer or distal lialf (outside the central capsule) ; both ends suddenly separated by 

 a constriction, in which is inserted the membrane of the capsule. The latter is pellucid, with a 

 number of yellow bodies. Apex of the spines simple, base pyramidal, without leaf-cross. 



Dimensions. — Length of the spmes 0-2 to 0'4, breadth of the basal half O'Ol, of the distal half 

 0-002 to 0-004. 



Habitat. — Atlantic, Canary Islands, Azores, Station 354, surface. 



Subgenus 2. Acanthonidium, Haeckel. 



Definition. — Spines at the central base with a broad leaf-cross, composed of four 

 prominent triangular lamella3 ; the meeting edges of these crossed lamellae between every 

 three or four neighbouring S2:)ines so rest one upon another that twenty-two hollow 

 pyramidal compartments are formed (compare p. 721). 



9. Acanthoma echinoides, Haeckel. 



Acanthometra echinoides, Claparede et Lachmann, 18.58, Iiltudes sur les Iiifusoires et les 



Rhizopodes, ifec, p. 459, pi. .xxiii. figs. 1-5. 

 Acanthometra echinoides, Haeckel, 1862, Monogr. d. Radiol., p. .383. , 



Spines quadrangular prismatic, without prominent edges, with four plane lateral faces, of equal 

 breadth throughout their whole length. Central base three to four times as broad, with large leaf- 

 cross. Apex truncated or bifid (sometimes with four short teeth). 



Diviensions. — Length of the spines 0-3 to 0-5, breadth 0-004 to 0-008 ; leaf-cross 0-02 to 0-03. 



Habitat. — North Atlantic, west coast of Norway (Claparfede et Lachmann); Freroe Channel 

 (Gulf Stream), John ]\Iurray, surface. 



10. Acanthoma claparedei, Haeckel. 



Acanthometra claparedei, Haeckel, 1862, Monogr. d. Radiol., p. 383, Taf. x\iii. fig. 12. 



Spines quadrangular prismatic, with four prominent lamellar edges, of equal breadth throughout 

 their whole length. Apex bifid. Central base twice as broad, with large leaf-cross. Central 

 capsule opaque, reddish-brown. 



Dimensions. — Length of the spines 0-6, breadth 0-016 ; leaf-cross 0-032. 



Habitat. — Mediten-anean (Messina) ; Atlantic, Station 347, surface. 



