REPORT ON THE RADIOLARIA. 555 



9. Myelastrum ciliatum, n. sp. 



Anterior arms trifid, with two shallow incisions. Posterior arms somewhat smaller, also trifid, 

 with two deeper incisions. Sagittal constriction a little larger than the transverse. Margin of the 

 disk ciliated, with radial bristle-shaped spines, as prolongations of the inner radial beams, arising 

 from the central disk. 



Dimensions. Eadius of the anterior arms 0'6, of the posterior 0'5 ; longitudinal constriction 0'4, 

 transverse 0'35. 



Habitat. South Pacific, Station 288, surface. 



10. Myelastrum lobatum, n. sp. 



Anterior arms somewhat broader but shorter than the posterior arms. Each arm four-lobed, 

 with three terminal shallow incisions of nearly equal size. Sagittal constriction smaller than the 

 transverse. Surface of the disk bristly. 



Dimensions. Eadius of the anterior arms 0'4, of the posterior O5 ; longitudinal constriction 0'3, 

 transverse 0'35. 



Habitat. North Pacific, Station 253, surface. 



11. Myelastrum rotula, n. sp. 



Anterior arms little broader than the posterior, but of the same length. Each arm four-lobed, 

 with three terminal deep incisions of equal size. Sagittal and transverse constrictions equal. The 

 whole disk nearly circular, resembles a wheel with sixteen spokes. Surface smooth. 



Dimensions. Eadius of all four arms 0'5 ; longitudinal and transverse constrictions 0'3. 



Habitat. Pacific, central area, Station 274, surface. 



12. Myelastrum giganteum, n. sp. 



Anterior arms somewhat broader and shorter than the posterior. Each arm four-lobed, with 

 three shallow terminal incisions, the middle incision twice as deep as the two laterals. Sagittal 

 constriction a little larger than the transverse. Margin ciliated, with radial bristle-shaped spines 

 as prolongations of the inner radial beams, proceeding from the central disk (as in Myelastrum 

 dodecaceros, PI. 47, figs. 11, lla). 



Dimensions. Eadius of the anterior arms 0'6, of the posterior O8 ; longitudinal constriction O6, 

 transverse 0'5. 



Habitat. Pacific, central area, Station 271, surface. 



