150 bulletin: museum of comparative zoology, 



PLATE IX. 



To illustrate the irregular development of the marginal tentacles belonging to 



the ti, to, and ^3 cycles. 



Figs. 1-6, 10, and 14 are normal sectors belonging to the third stage of development. 



Figs. 7-9, 12, 13, 16-19, and 22-26 show sectors belonging to the same stage of de- 

 velopment, but there has been great irregularity in the succession and 

 growth of the third cycle of tentacles. 



Figs. 20-22, 27, and 28 show sectors with only one tentacle of the ^3 cycle in each 

 primary division. 



Figs. 29 and 30 belong to the second stage of development . 



