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



dark nucleoli. Protoplasm filled up with numerous small clear vacuoles, and between them fine 

 red pigment granules; on the inside of the membrane one layer of dark oil-globules. Jelly-like 

 calymma four times as broad as the enclosed capsule, with very numerous small xanthellee. 



Dimensions. Diameter of the capsule 0'2, of the nucleus O'Oo, of the calymma 0'8. 



Habitat. Atlantic, Canary Islands (Lanzerote, Haeckel), 1866 ; also at Station 348, surface. 



4. Actissa radiata, n. sp. 



Central capsule spherical, dark, with a thick, double-edged membrane. Nucleus central, 

 spherical, half as large as the capsule, transparent. Protoplasm divided into numerous cuneiform 

 radial pieces which are separated by clear intervals, and filled with very fine dark granules (darker 

 in the distal half). The equatorial optical section exhibits around the circular clear nucleus a 

 coronal of twenty-five such wedge-shaped pieces (mother-cells of spores ?) No oil-globules in the 

 central capsule. Jelly-like calymma one and a half times as broad as the enclosed capsule, with 

 numerous small xanthellae. 



Dimensions. Diameter of the capsule 015, of the nucleus - 07, of the calymma 0'24. 



Habitat. North Pacific, Station 241, surface. 



Subgenus 2. Actiprunum, Haeckel, 1882. 

 Definition. Central capsule ellipsoidal, with one prolonged axis. 



5. Actissa prunoides, n. sp. 



Actiprunum prunoideum, Haeckel, 1882, Manuscript. 



Central capsule ellipsoidal, colourless, with a thin, simple-edged membrane. Proportion of its 

 major axis to the minor 4 : 3. Nucleus spherical, its diameter equal to one-third of the minor axis, 

 in its centre a large, dark, spherical nucleolus. Protoplasm clear, containing numerous small vacuoles, 

 separated by regular distances, and on the inside of the capsule-membrane, numerous (forty to fifty) 

 small oil-globules. Calymma (or jelly-veil) ellipsoidal, with a thin sarcode-stratum on the outside 

 of the capsule ; its diameter twice as large as that of the central capsule. 



Dimensions. Major axis of the capsule 016, minor 012 ; diameter of the nucleus - 04 ; major 

 axis of the calymma 0'32, minor 0'24. 



Habitat. Central Pacific, Station 274, surface. 



6. Actissa ellipsoides, n. sp. 



Actiprunum dlipsoides, Haeckel, 1882, Manuscript. 



Central capsule ellipsoidal, red-coloured, with a thick, double-edged membrane. Proportion of 

 its major axis to the minor 5 : 3. Nucleus ellipsoidal, one-third as large as the capsule, containing 

 eight small dark nucleoli. Protoplasm dusky, filled with dark pink pigment-granules; in the 



