530 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



A pair of Antennary nerves (n. a. 2 ) originate 

 behind the Tegunientary nerves. These long and slender 

 nerves pass outwards at right angles to the long axis of 

 the body till they turn sharply forwards towards the 

 second Antennae. 



The Brain is connected to the remainder of the 

 nervous system by a pair of long connectives — the 

 Oesophageal Commissures (cm.) — which arise close 

 together at the back of the brain and curve gently out- 

 wards round the oesophagus, to approximate again as 

 they approach the thoracic ganglion-mass. On either 

 side of the oesophagus each commissure dilates to form a 

 par-oesophageal ganglion, from which arise four nerves. 

 Both of the two outside branches are small ; the anterior 

 one, which is the smaller, innervates the surrounding 

 tissues, and the larger and posterior one supplies the 

 muscles of the mandible. 



S tomato gastric system (figs. 39 and 37). — The two 

 inside branches arise together and pass, diverging towards 

 the mid-line in front of the oesophagus where each joins 

 its fellow from the opposite side, to merge into a median 

 unpaired nerve passing vertically up the front of the 

 stomach. Three-quarters of the way up the anterior wall 

 this median stomatogastric nerve enlarges to form the 

 stomatogastric ganglion, from which several small 

 branches to the muscles and walls of the stomach arise. 

 The stomatogastric nerve then mounts the stomach and, 

 directly on attaining its dorsal surface, forms another 

 ganglion, which gives origin to several small nerves, and 

 finally terminates in a bifurcation above the pyloric 

 portion of the stomach. 



After leaving the par-oesophageal ganglia, the 

 commissures pass backwards and become attached close 

 together to the front of the ventral thoracic ganglion- 



