ANATOMY OF NEOHELIA PORCELLANA (mOSELEY). 601 



M.f. Mesenterial filament with gland cells {yl. c). 



N. Nematocysts on acontiuin. 



St. Stomodaeum. 



T. Tentacle. 



Tes. Testis. 



Fig. 4. T.S. through a single calicle showing the distribution of hard and soft parts. 

 About 60 diameters. The dotted portion represents the calcareous skeleton. 



The primary tentacles correspond in position with the primary septa, the secondary, 

 with the secondary septa, and so on. 



In the coenosarc outside the polyp peripheral lamella enclosing portions of the coelenteron 

 and forming a portion of the Endodermal canal system, are seen lying in the mesogloea. 

 (Caw.) 



Ca. Calcareous skeleton. 

 Cy. Position of calycoblasts. 

 Ec. Ectoderm. 

 En. Endoderm. 

 Mg. Mesogloea. 

 Mes. Mesentery. 

 P.S. Primary Septum. 

 S.S. Secondary Septum. 

 T.S. Tertiary Septum. 

 P.T. Primary Tentacle. 

 S.T. Secondary Tentacle. 

 T.T. Tertiaiy. 



Fig. 5. Surface view of a portion of coenosarc in the neighbourhood of an aperture 

 in the wall of colony. The aperture is surrounded by a specialized epithelial layer, .£;;. X., 

 which is encircled by an Endodermal Ring Canal, R. C. ; this gives off numerous branches 

 which ramify and anastomose in the coenosarc and connect the coelentera of the polj'ps. 

 (Cam. Luc. x 43). 



A. Aperture. 

 Can. Canals. 

 Coen. Coenosarc. 



Fig. 6. Section through Specialized Epithelium and Endodennal ring canal surrounding 

 hole in wall of colony (x 660. Iron Haematoxylin). 



The Epithelium contains : 1. Nematocysts similar to those on acontia. 2. Gland cells. 

 3. Interstitial cells. 



En. Endoderm. 

 GL Gland Cells. 

 In.C. Interstitial cells. 

 Mg. Mesogloea. 

 #. Unexploded Nematocysts. 

 R.C. Ring Canal. 



Fig. 7. A single exploded Nematocyst of Acontium showing spirally barbed thread. 

 x870. 



