40 

 the egfj of Turri ton sis in not as nuitablp for study during 

 lifp as these beautinilly transnarpnt o.f^.f^s of Lirione and 

 Eutina for instancp, which allov; all the changes that take 

 place '.vithin Lhe egg during develoi-neri? to be follovved easily. 



The soecific gravity of the eggs is greater than that 

 of sea-water and consequently they sink to the bottox of 

 the aquariuT, as soon as they are discharged froir, the cavity 

 of the urrbrella. In onacity Lhe egg of Turritc_sis is inter- 

 T-.ediate betv^een the egf^ oflStpniptoca rugpsa, which is extre~e- 

 ly dense and of aiohalky white color, and the egg of Stono- 

 toca an i cat a which is seni-transnarent and an^ears bluish- 

 white by reflected li^ht. In color the egg of Turritpnsis 

 is yellowish v.'hite. 



MATURATIGii AI-ID FE.^TILIZATIO:.. 



Because of the opacity of the egg satisfactory obser- 

 va^ions on the nhenc-ena of rraturation and fertilization 

 are ir-'Ossible during life, excent for those changes v/hich 



