63 



4. The trunk of the branchial arteries of the left side. 



5. 5. The branchial arteries. 



6. 6. Tlie glandular follicles connected therewith. 



u. One of the partitions forming the receptacle of a group of follicles. 

 u. u. The receptacles of the lesser groups of follicles attached to the anterior 

 branchial arteries, which are situated in the partition dividing the 

 pericardium from the branchial cavity. 

 10. 10. Tlie branchial veins. 



12. The lesser aorta. 



13. The branch going to the ovarian gland. 



14. The siphonic artery. 



15. The artery of the intestine. 



18. Tlie elongated shut sac which is connected at its extremities with the 

 ventricle and the venous sinus. 



PLATE VI. 



Fig. 1. The circulating and respiratory organs of Nautilus Pompilius. 



1. The great vein. 



r. The orifices by which it communicates with the abdominal cavity. 



2. The venous sinus. 



3. 3. The splanchnic veins from the Uver, ovary, gizzard, &c. 



4. 4. The origins of the branchial arteries. 



5. 5. The branchial arteries. 



6. 6. The follicles appended to the branchial arteries. 



7. 7. The orifices by which they communicate with the branchial arteries, ex- 



posed on the left side (the parts being seen from the dorsal aspect). 



8. The valve at the entry of the branchial artery into the gill, exposed in 



the right anterior vessel. 



9. The cavity of the same artery, where it is imbedded in r, the muscular 



stem of the gill laid open. 

 p. The larger branchia of the right side, showing the arterial surface. 

 p. The same of the left side, showing the venous surface. 

 q. Tlie smaller branchia of the right side, showing the arterial surface. 



