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g-anglia aie connected hv hrnad commissures passing- on 

 each side of the (psophagus, leaving only a narrow opening 

 for its passage. The sub-fjesophageal ganglion projects 

 slightly forward under the supra-oesophageal, giving it 

 the appearance of being separated from it, when viewed 

 from the ventral aspect (Plate III., fig. 2). These are 

 the only ganglia, and they supply the various parts of the 

 body with nerves. 



The supra-oesophageal ganglion is about half the size 

 of the sub-(esopliageal. It is produced on its dorsal 

 surface into an optic lobe (Plate III., fig. 5), from which 

 arises a distinct pair of optic nerves. Horizontal sections 

 of the optic lobe show that the roots of these nerves cross 

 each other (Plate III., fig. 12). Each optic nerve, there- 

 fore, is supplied by fibres from both sides of the brain. 



The nerves supplying the antennules arise from neai- 

 the anterior angles of the ganglion. They pass obliquely 

 forward to the base of the antennules, and there sub- 

 divide into a number of branches which pass to the sets? 

 clothing the anterior surface of the basal joint and apex 

 oi the second (Plate III., fig. 4). From the manner in 

 vrhich the antennules are supplied by this nerve it is 

 evident that they are important sensoiy organs (Plate III., 

 fig 4). 



The antennae are supplied by nerves arising from the 

 anterior angles of the ganglion, which pass anteriorly 

 \inder the nerves of the antennules and enter the base 

 of the antennse. These are the only appendages supplied 

 from the supra-(esophageal ganglion. 



The sub-opsophageal ganglion is heart-shaped, and fully 

 twice the size of the supra-cesophageal. It represents the 

 whole of the thoracic and abdominal ganglia of the higher 

 Crustacea, and supplies the remainder of the appendages. 



