PLATE XXT. 



M^;ANDRINA LABYRINTHICA (KIHs a Solander). 



Fi(i. 141. — Transverse section through the stomodfeal region of part of a ccilony, including four stonioda>a ami their 

 associated mesenteries. The number of mesenteries inserted on each stomoda'um is variable, and in 

 the portion represented no incomplete pairs occur. Tlie septal invaginations at this level are mainly 

 entocu'lic. The line of separation between each stomodieal system i)asses through two entocceles, never 

 tlirough an exoccele. Xo pairs of directives ever occur. The eudoderm is not represented. X 40. 



Fi(i. 142. — Transverse section at a still lower level, showing how the polypal cavity is encroached upon by the 

 ingrowth of the entosepta and their fusion in the middle. In some cases the interseptal loculi thus 

 produced are wholly distinct in section, but elsewhere several are in communication. The two 

 mesenteries included within each loculns belong to adjacent pairs, no exosepta being present. X 110. 



Fig. 143. — Section tlirough a mesenterial filament and the swollen part of the mesenterial endoderm innnediatelv 

 l)ehind. X :!20. 



Fig. 144. — Section through another filament, in wliii-h many nf the cells du the left side are filled with granular 

 contents. X 320. 



Fig. 145. — Section through a jiart of a mesenterial filament in which the cells have all become enlarged and 

 glandular, the modification having also affected the swollen endoderm behind (see p. 473). Three 

 granular gland cells are found iu the section, in addition to the clear gland cells. X 400. 



Fig. 14(1. — Section through a mesentery containing two ova. X 300. 

 640 



