ASTERIAS PALLIDA. 



269 



each other. Its cavity has also en- 

 larged considerably, so that it now 

 forms a spacious circular ring ar<xuid 

 the permanent œsophagus (Figs. 27, 

 28, 36, 38, 39). In the madreporic 

 interradius the ]>eriœsopliageal en- 

 teroc(el pushes in between the stom- 

 ach and the axial sinus and thus 

 confines the connection of the dorsal 

 mesentery with the stomach to a 

 very small area on the dorso-[)OS- 

 terior corner of the gut (Fig. 38). 

 Inmost of the figures representing 

 the ])eri(esophageal enterocœl in the 

 condition above descril)ed (Figs. 27, 

 28, 36, 38, 39) there is a thick 

 mesentery between it and the second- 

 ary left posterior enterocœl, but in 

 Fier. 37, which is taken from the 

 same series of sections as Fig. 38, 

 this mesentery has disappeared, and 

 the two cavities have become one. 

 Tliis coalescence of the two cavities 

 takes place at all points, and in the 

 complete star there is but one large 

 cavity on the oral side of the gut, and 

 Ave have then absolutely no means 

 of reco<'-nizino- the former existence 

 of the periœsophagealenteroc(el.* 



* In my preliminary papers I stated that the mesentery in question seems to persist 

 throughout life in the madreporic interradius. Further examination of more advanced stages 

 has shown that the statement is erroneous. 



