DR. TH. MOETENSEN. 



seven days (the 19th) the stage represented in Figures 1-2 was reached. 

 For the next two weeks there was no further differentiation, and I nearly 

 gave up the hope of getting it to proceed in its development, thinking 

 that the diatoms were perhaps not suitable food for this larva ; indeed, 

 I found that the diatoms ejected by it had the same colour as those 

 which had not been swallowed, so it appeared that the larvae could not 

 digest the diatoms. But on the 4th July I found some specimens in 

 which the left enterocoel vesicle had begun to grow forwards, and now 

 the development went on continually. On the 7th July the enterocoel 



Fig. 3. Fig. 4. 



Figs. 3-4. — Bipinnaria of Asterias glaciaUs, four weeks old. 3, front view ; 

 4, side view. 80/1. 



vesicles had united in the preoral lobe, and the long processes had begun 

 to develop. The stage represented in Figures 3-4 was reached on the 

 9th July. When I left Plymouth, on the 15th, no essential advancement 

 beyond this stage could be observed, and a few larvae sent to me later on 

 were not in a more advanced stage either. I am thus unable to give 

 definite information of the specific characters of the fully developed larva. 

 Judging from the figures given by Delage, the larva of A. glaciaUs 

 ■differs from the larva of A. rubens and vulgaris, the only two other species 

 known to which it is similar, in the sucking disc at the basis of the 

 b>rachiolarian processes being surrounded by a complete ring of small 



