272 BULLETIN OF THE 



Fig. IS. Ophiomyxa pentagona (Mediterranean). Skeleton of mouth-parts and 

 arm, as far as edge of disk, seen from above. The radial shields, 7, are turned 

 upwards and outwards, so as to expose the peculiar forked genital plates, o. v, 

 stout triangular pieces covering the trench of the nerve-ring. These in Ophi- 

 oglypha ciliata appear only as thin plates, j, little rudimentary upper arm-plates, 

 split in two. s, supplementary pieces lying within the skin, along the disk 

 margin ; {■. 



Cambridge, February 15, 1S74. 



