b) .If the latter view is the correct one then 



radial canal 3. points toward the same end of the 



the larva in both "C" and "D'J Figs. G and 9., but 



in "C" the end toward which it points is anteriorly 



directed in swimming and in "D" it points away from 



the end which precedes. It is hardly thinkable that 



at any stage in its development, the anterior end 



of a larva should chance its physiological function 



and become the posterior end. 



c).3y any other view than the one I have adopt- 

 atiluo \i*^ j&jaa* V*- <uu& , 



ed jthe blastopores ,c t it-' n^ginfil pnsUrJr&fswould 



be anterior and the larval organ would be posterior 

 in position. In all known echinodem larvae the bias- 

 topore marks the posterior end of the larvae and in 

 all cases where it occurs the larval organ origin- 

 ates from the anterior end. 



d) ,It may be recalled, as having en indirec t 

 b-er-r^r; e ri **-■ qu -'--'• i r >h , that in the readjustment 

 of parts which takes place during the metamorphosis 

 of other c-chinoderm larvae the rotation is almost 

 entirely confined to the hydrocoele . 



As the hydrocoele passes round the oesophagus 

 the tube connecting it with the left horn ef the 

 hypogastric enterocoele becomes broken and the left 



