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



median lobe is longer than the lateral lohe. Sagittal constriction little smaller than the transverse. 

 Surface of the disk rough. 



Dimensions. Eadius of the anterior arms 0'45, of the posterior 0'62 ; longitudinal constriction 

 0'25, transverse 0'3. 



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



5. Myelastrum farfalla, n. sp. (PL 47, fig. 10). 



All four arms with a shallow incision at their distal end. Anterior arms broader, but shorter 

 than the posterior ; in each arm the anterior lobe is shorter than the posterior. Sagittal constriction 

 smaller than the transverse. Surface smooth. 



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

 transversal stricture 0'6. 



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



6. Myelastrum papilio, n. sp. (PL 47, fig. 6). 



All four arms with a shallow incision at their distal end. Anterior arms triangular, of the same 

 breadth, but of the double length of the square posterior arms. Sagittal and transverse constric- 

 tions of the same length. Surface ciliated. (Eesembles a butterfly.) 



Dimensions. Eadius of the anterior arms 0'7, of the posterior 0'4 ; longitudinal and transverse 

 constrictions 0'4. 



Habitat. North Pacific, near Japan, Station 241, surface. 



7. Myelastrum decaceros, n. sp. (PL 47, fig. 7). 



Anterior arms bifid, with one shallow incision at their distal end. Posterior arms of the same 

 length, but much broader, trifid, with two incisions (one larger and one saaller). Sagittal and 

 transverse constrictions of the same length. Surface spiny. 



Dimensions. Eadius of all four arms 0'4 ; longitudinal and transverse constrictions - 35. 



Habitat. Pacific, central area, Station 272, surface. 



8. Myelastrum dodecaceros, n. sp. (PL 47, figs. 11, lla). 



Anterior arms trifid, with two shallow incisions at their distal end. Posterior arms about one- 

 third larger, also trifid, with one deeper anterior and one shallower posterior incision. Sagittal 

 constriction much longer than the transverse. Surface ciliated, covered with numerous thin and long 

 radial bristles (fig. lla). 



Dimensions. Eadius of the anterior arms O5, of the posterior 0'7 ; longitudinal constriction 0'5, 



transverse 0'35. 



Habitat. Pacific, central area, Station 270, surface. 



