Cer 36 



Cerebral ganglion. — The nervous system of insects 

 is characterised by the great size which the 

 cerebral ganglion attains. The most anterior 

 of the ventral series, the subcesophageal, is 

 situated in the head, like the cerebral ganglion, 

 and gives o£E branches to the mouth-parts. 

 This is succeeded by three single or paired 

 ganglia, one for each thoracic segment, and 

 lastly by a series of abdominal ganglia. Often, 

 however, some of these fuse ; the second and 

 third thoracics may for instance ; the posterior 

 abdominals also, or the second and third 

 thoracics and all the abdominal ganglia may 

 unite to form a single mass, which, in extreme 

 cases, includes also the first thoracic ganglion. 

 (Boas.) (L. cerebrum., brain, and ganglion.) 



Cerebroidae. — The knots in which the difEused 

 brain of insects is centred. Capitis cerebroida. 

 (L. cerebrum, brain.) 



Cerebellum. — Generally a cordiform or longitudinal 

 ganglion ; it lies at the base of the skull , between 

 the two projecting ridges of the internal 

 skeleton of the head, and is entirely covered by 

 the tentorium. The nerves which pass from the 

 cerebellum are the nervi mandihularum, the nervi 

 maxillarum, and the nervi labii (Burmeister.) 

 (L. a little brain.) 



Cerebrum. — A nervous cord of a yellowish-white 

 colour, lying transversely across the oesophagus, 

 generally forming two ganglia. Its entire 

 circimiference is covered with a thin transparent 

 membrane, which loosclv surromids it. The 



