658 'Journal of Comparative Neurology and Psychology. 



Fig. 2. A transverse section through the ventral lobes in the region of the origin of the oesophageal 

 nerves, and showing the first pair of neurocord cells. Obj. AA, oc. 4, tube length 170 mm. rrti, right 

 neurocord cell of the first pair; ln\, left neurocord cell of the first pair; en, oesophageal nerve; jc, fibrous 

 core; cs, cellular sheath. 



Fig. 3. A transverse section through the ventral lobes and the third ventral commissure, showing 

 also the left neurocord cell of the third pair. Obj. AA, oc. 4, tube length 170 mm. In^ left neurocord 

 cell of the third pair; 5, third ventral commissure, with two roots on the right side. 



Fig. 4. Part of a transverse section, showing the right neurocord cell of the fourth pair, and the 

 unpaired neurocord cell. Obj. homog. immers. jV, oc. 2, tube length 160 mm. rrii, right neurocord 

 cell of the fourth pair; uc, unpaired neurocord cell; ren, outline of right oesophageal nerve; jc, fibrous 

 core of the right brain lobe; DV, dorso-ventral axis of the right oesophageal nerve. 



Figs. 5 and 6. Parts of two consecutive sections through the ventral lobes, showing the fifth ven- 

 tral commissure. Obj. AA, oc. 4, tube length 160 mm. 5, fifth ventral commissure: ^c, central part 

 of fifth ventral commissure. 



