72 



SIB C. WTTILLE THOMSON ON THE MODE OE 



charge of ova into the passages, so that eggs and young in different 

 stages of development occupj the spaces at once. The young do 

 not escape until at least six ambulacral suckers are formed on 

 each arm ; they may then be seen pushing their way out by 

 forcing the paxilli to the side, and squeezing through the chink be- 



Fig. 10. 



A'lxhaste)' exctivatus, Wv. Thomson. Twice the natural size. 



