14 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. -J-] 



gard the sclerites of the neck in insects as secondary developments. 

 Likewise, embryology has not demonstrated a fourth component 

 in the insect subcesophageal ganglion. VerhoefT's idea of the quad- 

 ruple structure of this ganglion should not be confused with the 

 claim, now pretty well discarded, that the ganglion comprises a 

 pair of ganglionic centers between those of the mandibles and the 

 maxillae, innervating the lateral lobes (superlinguse) of the hypo- 



Fin. 6. — Diagram of a typical arrangement of ganglia in the stomato- 

 gastric nervous system. 



FrGng, frontal ganglion, connected with tritocerebrum by frontal 

 commissures {l-'rCom) and giving off posteriorly the recurrent nerve 

 (RNv) to oesophageal ganglion (CEGng) ; the latter connected by 

 lateral nerves vi^ith lateral ganglia {LGng), each of which is united with 

 back of brain by small nerve («), and by median nerve with gastric 

 ganglion (GGng). 



pharynx. A more detailed investigation of the internal structiu-e 

 of the subcesophageal ganglion, which has been less studied than 

 that of the brain or the body ganglia, should be made before any 

 definite statement can be given of the exact composition of the 

 ganglion or the homologies of its posterior nerves. 



THE STOMATOGASTRIC NERVOUS SYSTEM 



The ganglionic centers of the stomatogastric nervous system are 

 located on the dorsal surface of the stomodeal parts of the ali- 

 mentary canal, from the epithelium of which they are formed in 



