NERVOUS SYSTEM OF DECOLOPODA 129 



left arises similarly from the commissure, while that on the right arises from the 

 gangUonic mass (as in D. australis, Fig. 73 A). 



Wiren (1918, p. 80, fig. 16) illustrates a nerve, designated as No. 5, arising from near 



a 



Fig. 73. Decolopoda australis. Eights: A. Central nervous system: x 13. 

 Decolopoda antarctka, Bouvier. B. Supra-oesophageal ganglia and their 

 associated nerves (diagram). C. Optic nerve and its branches below the 

 ocular tubercle : x 13 



a. Median azygous proboscidial nerve, b. Optic nerve, c. Nerve to chelo- 

 phore. d. Nerve to muscle working chelophore. e. Superficial nerve to 

 anterior border of cephalon. i, 2 and 3. Nerves to proboscis, palp and 

 oviger respectively. 



the base of the circum-oesophageal commissure in Colossendeis; this nerve (1918, 

 pp. 73-4) passes right forward to the base of the proboscis, near to the point of insertion 

 of the palp, to innervate muscles. In D. antarctka I have been unable to discover this 



17 



