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and at the same time increasing in size. Immediately in front of the 

 commencement of the gizzard they unite in a triangular ganglion, 

 from which many filaments radiate, forming a plexus upon the giz- 

 zard, and disappearing on the vesicular coeca. 



Coleopfera. In Dytiscus marginalis the sympathetic nerve is so 

 large and distinct, that it may easily be traced by the unaided eye. 

 It arises by two very slender roots from the anterior part of the brain, 

 a small ganglion being formed by their union in the anterior and 

 upper part of the head. The trunk of the nerve at its first origin 

 from this ganglion is very slender, but gradually increases in size in 

 its course along the oesophagus. It also gradually bends towards 

 the left side of the canal and of the first stomach, closely following 

 the curves of the latter. Before the termination of the first stomach 

 it expands into a second and smaller ganglion, from which two 

 filaments diverge, to ramify on the second and the beginning of 

 the third stomach, 



In the Stag-beetle (Lucanus cervus), the frontal ganglion appears 

 as a white triangular mass, situated in front of the brain, with which 

 it is connected by means of two lateral loops. Posteriorly, it is. 

 elongated into a very delicate filament, which, passing below the 

 brain, accompanies the narrow O2s<~phagus for a short space, and 

 then bifurcates without expanding into a ganglion ; at this point 

 the branches become so minute, that they can no longer be traced 

 even by the aid of glasses. 



As the larvae of the herbivorous Coleoptera with lamellated an- 

 tennae present a very complicated structure of the alimentary canal, 

 as compared with the perfect insects, there is ground for supposing 

 that the recurrent, or sympathetic nerve, may be developed in a 

 corresponding degree, particularly when we consider that, in the 

 larva of the rhinoceros beetle, according to Swammerdam and 

 Cuvier, it swells into two ganglia, and accompanies the whole in- 

 testinal canal. If such be the case, it would farther follow, that 

 during the process of metamorphosis, the visceral system of nerves 

 must undergo changes analogous to those which are known to take 

 place in the abdominal chain of ganglia, and corresponding to the 

 changes which take place in the organs on which it is distributed, 



Hemiptera. The observation by J. F. Meckel, of the existence 

 of a recurrent nerve in Tdtigonia plebeia, presents all that is yet 

 known as far as regards this order of insects. 



Lepidoptera. In the larva of a large sphinx, Dr. Mueller ob- 

 served the same relations of the recurrent nerve as in the descrip- 

 tions by Lyonnet and Swammerdam, of the Phalaena cossus and 

 Bombyx mori. 



Hymenoptera. As already mentioned, the recurrent nerve has 

 been discovered by G. Treviranus in the common bee. 



Crustacea. In the cray-fish (Astacus fluviatilis), Dr. Mueller 

 supposes that he has seen an elongated frontal ganglion, which 

 extends upwards and downwards, ramifying on the stomach, and 

 communicating by short and delicate filaments with the brain. The 



