THE NEUROMUSCULAR STRUCTURE 85 



may be described briefly in the following order beginning 

 with those in the ectoderm. 



1. The longitudinal mnscle of the tentacle is an elon- 

 gated conical sheet of ectodermic fibers that are in direct 



Fia. 20. Diagram of a partial longitudinal section of the sea-anemone Metridium show- 

 ing the thirteen classes of muscles: 1, longitudinal muscle of the tentacle; 2, radial muscle 

 of the oral disc; 3, circular muscle of the ossophagus; 4< circular muscle of the oral disc; 5, 

 circular muscle of the tentacle; 6, circular muscle of the column; 7, sphincter; 8, circular 

 muscle of the pedal disc; 9, basilar muscle; 10, longitudinal muscle of the mesentery; 11, 

 transverse muscle of the mesentery; 1%, parietal muscle; IS, longitudinal muscle of the 

 acontium. 



contact with the supporting lamella. They course length- 

 wise in the grooves and on the crest-like elevations that 

 extend up and down the outer surface of the lamella, and 



