EUPAGURUS. 529 



above the epistoma. It is transversely ovate from above, 

 and a bi-lobed appearance is given to it by a shallow 

 median depression. 



The nerves supplying the principal sense organs and 

 the circuni-oesophageal connectives with their offshoots 

 arise from the brain, and branches are also given to the 

 surrounding tissues. 



Optic nerves (n. op.). — A pair of nerves arise in the 

 front of the brain and pass, diverging slightly, into the 

 eye-stalks. Immediately after passing the base of the 

 peduncle the nerve swells to form a small ganglion, from 

 which fibres supplying the eye muscles arise, and ends 

 in another enlargement under the retina. 



Oculo-motor nerve (n. m. o.). — The muscles of each 

 eye and its adjacent parts are innervated by a much 

 smaller nerve, which pursues a track parallel to and 

 outside of each optic nerve. 



The Antennulary nerves (n. a. ± ) are really four in 

 number, but owing to the fact that the nerve supplying 

 the first antenna and that supplying the otocyst have 

 coalesced on either side, a single pair only is visible. 

 This pair arises from the under surface of the posterior 

 half of the brain. Each nerve is broad and has but a 

 short course, plunging downwards and forwards on 

 leaving the brain into the peduncle of the limb, where it 

 divides into auditory and tactile and muscular branches. 



The Tegumentary nerves (n. teg.) arise on either 

 side of the brain, slightly above and behind those 

 supplying the first Antenna. Each nerve is broad and 

 prominent, and passes outwards and slightly forwards, 

 surrounded by the mass of excretory gland which 

 envelops the hinder part of the brain. It branches 

 frequently and supplies the integument and other tissues 

 in the front of the head. 



