ON THE EXPEKIMENTAL HYBRIDIZATION OF ECHINOIDS. 347 



are sexually mature — are always obtained, some of which are in all probability 

 hybrids. 



15. It is hoped to obtain a second hybrid generation from the urchins at present 

 being reared. This is rendered the more hopeful since a number of our hybrids have 

 formed their genital pores. 



16. We have established that E. miliaris can become sexually mature well within 

 the first year of its existence, both in the state of nature and when raised from the 

 egg in the laboratory. 



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2 Y 2 



