542 



OLWEN M. EEES. 



dermal muscle. The endoderm consists of a spongy layer, which is about 

 the same thickness as the ectoderm, and this is full of colonies of 

 zooxanthellse. These do not stain with borax carmine, but appear 

 as brownish granules arranged in groups. 



FiCr. 11. — Antlioplcura alfordi. Section 

 through the sphincter muscle. 



-nem. 



Fig. 12. — Anthopleura alfordi. Vertical section 

 through the peristome ■wall, showing a fold, 

 and the origin of a mesentery. 



In a longitudinal section through a tentacle the ectodermal muscle can 

 be seen as a thin plate of tissue arising from the more deeply stained 

 mesogloea. Lobes and stunted irregular processes penetrate the endoderm. 

 Full-sized[nematocysts are situated near the outer edge of the ectoderm, 



