382 



ROBERT TRACY JACKSON ON ECHINI. 



TEXT-FUis. 245,246. — Melonechinus muUipoms. 

 X 2. Adapted from original drawing of Plate 57, fig.l. 



245. Showing typical character of ambuhicruni. 

 also ventral developing and dorsal localized stages. 



246. Interambulacnnn showing number of rows on 

 the left, and the introduction of columns on the right. 



