BUSYCON 



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united with each other and with the cerebral ganglia and 

 send nerves to the mouth apparatus. 



2. The large pedal ganglia, fused together but distinctly- 

 paired, lying posterior to the buccal ganglia and sending 

 nerves to the two sides of the foot. Each is united by con- 

 nectives with the corresponding cerebral and pleural ganglia. 



From the dorsal side a number of ganglia may be seen, 

 more of which lie to the right than to the left of the median 



line. 



1. On the left side there are two ganglia that are in 

 rather close union with each other. The most anterior, the 

 left cerebral, is the larger of the two. The left pleural joins 

 it posteriorly and ventrally and extends nearly to the ventral 

 side of the esophagus. 



2. On the right side four ganglia may be distinguished. 

 The right cerebral and right pleural are fused to form one 

 mass, but there is a marked constriction between them. Pos- 

 teriorly and dorsally the right pleural is connected by a con- 

 nective with the right parietal (supra-intestinal), which lies 

 very close to it. The remaining ganglion, the left parietal 

 (subintestinal) , which is almost in contact with the right 

 pleural and right pedal ganglia, lies ventrally and to the 

 right of the right parietal ganglion. It is connected with 

 the left pleural ganglion by a connective that runs behind the 

 pedal ganglia. There seems also to be a connection with the 

 right pleural ganglion, but this must be considered a secon- 

 dary connection. Do you understand how this ganglion comes 

 to have this position? 



3. Another ganglionic mass, the visceral ganglion, possi- 

 bly formed by the fusion of two ganglia, lies just below the 

 external opening of the kidney, where it can be seen as a 

 brown mass through the body wall. It lies on the elongated 

 commissure that connects the two parietal ganglia. The com- 

 missure may be followed by dissection. 



The cerebral ganglia are the most centralized. Besides 

 being connected with each other by a commissure dorsal to 



