From the anterior Tree- end of the archenteron 

 a large pouch is in process or being cut off .This 

 pouch projects to the right and left as horn like 

 processes which latter are to be considered &a the 

 rudiments &£ frho rudimsnta or the right and left 

 anterior entsrocoeles.Fig.2. wi *-*- oudL. 



As to the method of gastrulation I can not at 

 present speak from observation on larvae in which it 

 is just taking place but from a study of the stage 

 now under consideration, some idea can be gotten 

 as to how it has proceeded. In Figs.l and 3. we see a 

 cellular plug nrotruding from the blastopore and also 

 extending far into the archenteric cavity. In some 

 cases it extends even into the enterocoele pouch. 

 The contour of this cellular mass is ragged &e is 

 also true of both the outer and inner surfaces of 

 the wallof the archenteron and the inner surfs ce of 

 the rctezierre. 



These facts seem to indicate that gastrulation 

 does not take place by invagination, as is usual in 

 echinoderms.but that the larva before gastrulation 

 is a solid, planula like, affair, and later the arch- 

 enteron is formed by a splitting away of the central 



