EXPLANATION OF PLATE VI. 



FIG. II. Aptysia californica. Dorsal view. I, nerve to osphradium ; 2, branch to 

 roof of gill chamber; 3, nerve to viscera ; 4, nerve to gill; 5, nerve to dorsum of 

 the anal region ; 6, nerve to liver, ventricle and reproductive glands ; 7, nerve to 

 pericardium, kidney and auricle ; 8, branches to kidney ; 9, branch to auricle ; IO, 

 branch to liver ; II, branch to the reproductive gland ; 12, branch to aortic sinus ; 

 13, nerve connecting right pedal and visceral ganglia. 



FIG. 12. Pleurobranchrea californica. Dorsal view. I, nerve to osphradium and 

 gill ; 2, nerve to viscera ; 3, accessory visceral ganglion ; 4, genital nerve ; 5, nerve 

 to pericardium and auricle ; 6, 8, branches to pericardium ; 7, nerves in the walls of 

 the auricle ; 9, branch pericardium and aortic sinus ; IO, branch to aortic sinus ; II, 

 ganglion on aortic sinus ; 12, branch to the lateral artery ; 13, branch to posterior 

 artery ; 14, branch to aortic sinus, probably entering the ventricle. 



FlG. 13. Bulla globosa. Dorsal view. I, ganglia on left visceral nerve; 2, 

 nerve to dorsum of neck ; 3, commissure between the right and the accessory visceral 

 ganglia; 4, commissure between the left and the accessory visceral ganglia ; 5, nerve 

 to osphradium, gill and roof of gill chamber ; 6, nerve to inferior pallium and dor- 

 sum ; 7, accessory visceral ganglion ; 8, nerve to viscera ; 9, ganglion on visceral 

 nerve; 10, genital nerve; II, branch to aortic sinus and aorta; 12, nerve to pericar- 

 dium, kidney and auricle ; 13, branch to auricle ; 14, branch to kidney. 



FIG. 14. Montereina nobilis. Dorsal view. I, branch of visceral nerve passing 

 ventral to the hind gut ; 2, branch to ganglion on the aortic sinus ; 3, branch to peri- 

 cardium ; 4, branch to base of auricle ; 5, branch to gill ; 6, ganglion on the aortic 

 sinus. 



FIG. 15. Triopha carpenteri. Dorsal view. I, 2, nerves to the mantle ; 4, left 

 visceral nerve ; 6, right visceral nerve ; 7, nerve to genital ganglion ; IO, branch to 

 anterior aorta ; n, branch to gill and auricle. 



FlG. 16. Triopha grandis. Dorsal view. I and 2, nerves to dorsum and gill ; 

 3, reno-cardiac nerve; 5, ganglion on the reno-cardiac nerve; 7, nerve aorta and 

 ventricle ; 8, auricular nerves ; 9, ganglia at the base of the gill ; 10, optic nerve. 



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