H. H. NEWMAN. 



4 



5 



8 



IO II 12 



FIGS. 412. Camera lucida outlines of optical sections of a series of 

 subnormal larvae derived by spontaneous parthenogenesis from eggs of Patiria 

 ininiata. In these larvae the ectoderm in the region opposite the blastopore 

 is frequently thickened and also very frequently invaginates to form secondary 

 archentera. These thickenings do not occur in normal larva as may be seen 

 by comparing these figures with Figs. 13-21. 



