276 ANATOMY. 



portions of the nervous system lying before and behind it there ori- 

 ginate from it on each side from two to four nervous stems, which pass 

 to the mouth and the muscles of the head, and terminate in the various 

 organs constituting the mouth ; they are : 



1. The nerves of the mandibles (PI. XXXI. and XXXII. e, e), 

 which pass out of the anterior portion of the cerebellum, sometimes 

 between the branches of the loop of the oesophagus (Melolontha, PI. 



XXXI. f. 5.), sometimes from the exterior margin, contiguously to 

 them (Calosoma, PI. XXXII. f. 1.), and sometimes closer to the pos- 

 terior margin, beyond them (Gryllus, PI. XXXI. f. 7-)- They give off 

 several delicate auxiliary branches to the flexor and extensor muscles of 

 the mandibles ; and lastly, accompanied by branches of the tracheae, 

 they pass into the cavity of the mandibles themselves, between the 

 tendons of both muscles. In the caterpillar of Cossus, according to 

 Lyonet, the nerve of the mandible conies in a remarkable manner as a 

 branch from the labium, and this receives four main stems (PI. XXXI. 

 f. 2. e, e.). 



2. The nerves of the maxillae (PL XXXI. and XXXII./,/. and 

 f *,/*) originate sometimes in front (Calosoma, PI. XXXII. f. 1.), 



sometimes behind (Melolontha and Gryllus, PL XXXI. f. 4. and 7-)> 

 the nerves of the mandibles from the cerebellum, and run closely to these 

 to the maxillae, taking their course between the muscles, and passing 

 into the maxillae themselves. Here each divides, one branch going to 

 the palpus and extending to its apex, the other remaining in the maxillae, 

 spreading itself between its muscles. Sometimes (as in Calosoma, PL 



XXXII. f. 1. f, f. and f*, /'*.) these branches are divided at their 

 origin, and then the anterior one belongs to the maxillae and the pos- 

 terior one to the palpi ; both give off, even in the cavity of the head, 

 several branches, which pass to the neighbouring muscles. 



3. The nerve of the labium (PL XXXI. and XXXII. g, g.~) comes, 

 when separated from those of the maxillae, from the centre of the 

 anterior margin of the cerebellum, and runs from here, very closely to 

 its opponent, direct to the labium, and here divides itself into several, 

 generally two, main branches, the inner one of which goes into the 

 tongue and the outer one to the labial palpus. Where this nerve is 

 wanting (Melolontha, PL XXXI. f. 5.) branches of the nerves of the 

 maxillae supply its place, and this is precisely the case where the 

 tongue is small, hard, and cartilaginous. But it struck me as more 

 singular in the Locuxla (the same, f. 7-) 5 which, notwithstanding that 



