Ada Acad. Natura Curiosa Bounce. 589 



that have been almost wholly neglected by systematic writers. 

 Meckel and Treviranus alone have expressed their belief of its 

 analogy with the sympathetic nerve of vertebral animals; the latter, 

 in particular, has endeavoured to show that it corresponds to this 

 nerve only, and not to the par vagum, with which Mercel de 

 Serres is somewhat disposed to identify it. 



The term recurrent, by which it has usually been designated, is 

 far from being* generally applicable. In fact, it is only in Coleoptera 

 and Lepidoptera, that such is the case: in Orthoptera it arises 

 directly from the posterior margin of the brain. From the mode of 

 its distribution to the viscera only, and especially to the stomach 

 and intestine, to the complete exclusion of the voluntary muscles, 

 the name of visceral nerve is in every respect more suitable. 



The following descriptions will serve to show the extent to which 

 this discovery has been already pursued, and to give a general 

 idea of the ordinary arrangement of the visceral nerve. 



Orthoptera. In Phasma ferula, which is herbivorous, the brain 

 is situated beneath the commencejnent of the oesophagus, and the 

 usual nervous ring is wanting. The visceral nerve originates in a 

 small ganglion placed on the dorsal surface of the oesophagus, and 

 communicating by several minute filaments with the anterior part 

 of the chain of ganglia on the abdominal surface. The ganglion 

 thus formed sends a small filament forwards to the corslet, and is 

 continued posteriorly into a long and thicker cord, which, accom- 

 panied by a large trachea, is prolonged almost as far as the mus- 

 cular stomach (gizzard). In the middle of the second thoracic 

 segment, at the same point where the trachea bifurcates, the visceral 

 nerve forms a second ganglion, oval and considerably larger than 

 the first. In the interval between the two ganglia it gives numerous 

 delicate branches to the oesophagus. A great number radiate from 

 the second ganglion, to form an extended and most delicate rete in 

 front of the gizzard ; two, much larger than the rest accompany the 

 divisions of the trachea, and, like them, are distributed to the coats 

 of the stomach. 



In Mantis cpgyptiaca, (carnivorous), there is a considerable white 

 ganglion upon the gizzard, from which large branches radiate in all 

 directions, forming a plexus on the capacious membranous stomach 

 in front of the gizzard, penetrating the very short intestine, and 

 extending even to the coecal pouches, or supposed biliary organs. 

 Anteriorly, the ganglion is continued along the posterior surface of 

 the membranous stomach and oesophagus into a filament, which 

 gives off alternate branches as it advances forwards, becoming 

 gradually smaller in its course. 



In Gryllotalpa vulgaris (the Mole Cricket,) two nervous fila- 

 ments of considerable size arise from the posterior edge of the brain, 

 which immediately unite to form the trunk of the visceral nerve. 

 From this are immediately detached two chords, which extend for 

 the space of about an inch along the oesophagus and membranous 

 stomach, as far as the gizzard, giving off branches in_ their course, 



