PLATE VIII. 



Eaeth Worm [Lumhricus Terrestris). 



The fifteen anterior segments of an Earth Worm {Lumbricus Terrestris), numbered 

 from before backwards, the upper lip counting as the first segment. 



The integ-ument has been divided^ except in the first segment, 

 down the middle dorsal line, and the greater part of the dig-estive 

 tract has been removed, together with the pseud-haemal vessels, 

 so as to show the nervous, muciparous, and reproductive organs. 



a I. Bilohed supra-oesophageal ganglionic mass; giving off from 

 either outer angle a nerve which bifurcates very soon after 

 its origin, and passes to distribute itself in the tactile upper 

 lip. 



a 2. Visceral or stomatogastric system of the right side, con- 

 sisting of a long ganglion lying upon the lateral wall of the 

 pharynx, and running jmrallel with the cord of commissure 

 between the supra-oesophageal and the sub-oesophageal gan- 

 glia, with which it communicates by several roots anteriorly, 

 as it does posteriorly with a reticulate ganglionic plexus upon 

 the posterior part of the pharynx. This plexus lies imme- 

 diately externally to the mucous lining of the pharynx, 

 and some of the glandular and muscular tissues of its 

 outer walls must be cleared away in order to demonstrate 

 it clearly. Figured roughly by Morren, /. c. Tabs, xix.-xxi., 

 figs. I and 2 k. I. ; and described more accurately by Qua- 

 trefages, Ann. Sci. Nat., Ser. iii., torn, viii., 1847, p. -^6. 



a 3. Commencement of chain of ventral ganglia. The ventral 

 chain consists here, as in Arthropoda, of fibrous elements 

 p a 



