REPORT ON THE RADIOL ARIA. 555 



9. Myelastmm ciliatum, n. sp. 



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

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

 disk cihated, 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. Myelastru'm lohatum, 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 0'5 ; longitudinal constriction 0'3, 

 transverse 0'35. 



Hahitat. — 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 cu'cular, 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 racUal beams, proceeding fi'om the central disk (as in Myelastntm 

 dodccaccros, PI. 47, figs. 11, 11a). 



Dimensions. — Eadius of the anterior arms Oil, of the posterior 0'8 ; longitudinal constriction 0'6, 

 transverse 0'5. 



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



