74 



ZOOLOGY 



retractor muscles, only two of ^their mesenteries are continued 

 below the level of the oesophagus and bear mesenteric fila- 



FiG. 52. — A longitudinal section through a 

 polyp of Pennatvia phosphorea. After 

 Marshall. 



1. Mouth. 



2. Walls of stomodaeum. 



3. Free edges of mesenteries below the level of 



the stomodaeum, showing short mesen- 

 terial filaments. 



4. Long mesenterial filaments. 



5. Feathered tentacles. 



6. Calyx. 



7. Spicules in body-wall. 



8. Spermatospheres. 



9. Mesentery showing protractor and retractor 



muscle fibres. 



10. Coenenchyme. 



ments, they have a well-developed siphonoglyph, but no repro- 

 ductive system. 



The cavities of all the individuals are put into communi- 

 cation by means of a number of ramifying coenosarcal tubes 

 lined by endoderm. 



The Penhatulidae are phosphorescent, and emit a bright 

 glowing light when disturbed, this is said to originate from 



