ANATOMY OP NAUTILUS POMPILTUS. 41 



vations, however, and Van der Hoeven's figures, of both male and 

 female, lead me to believe that the peduncles of the branchiae 

 are perfectly distinct from one another. 



The follicles of the branchial arteries are thus described in the 

 " Memoir on the Pearly Nautilus :" — " They are short and pyri- 

 form and closely set together. To each of the branchial arteries 

 are appended three clusters of these glands, of which one is larger 

 than the united volume of both the others ; and the larger cluster 

 is situated on one side of the vessel and the two smaller on the 

 opposite side. Each of these clusters is contained in a membra- 

 nous receptacle proper to itself, partitioned off, as it were, from 



the pericardium, but communicating with it The two canals 



which form the communication between the pericardium and the 

 branchial cavity commence at the receptacle of the lesser cluster 

 attached to the superior branchial arteries, and terminate at the 

 papillae before mentioned, which are situated at the roots of the 

 branchiae. The pericardium and these receptacles of the glands, 

 when first laid open, were found filled with a coagulated substance 

 so closely compacted as to require a careful removal, bit by bit, 

 before the contained follicles and vessels could be brought into 

 view." 



Like Yalenciennes and Yan der Hoeven, I have been unable to 

 find any communication between the four sacs in which the small 

 double clusters of follicles are contained, and the " pericardium ;" 

 and I hold it to be certain that the other four sets of follicles are 

 not contained in sacs at all, but lie free in the " pericardium " or 

 posterior chamber. 



No notice is here taken of the widely different characters of the 

 anterior and posterior follicles ; and the figure gives both a similar 

 structure. 



Valenciennes (" Nouvelles Eecherches sur le Nautile Flambe," 

 * Archives du Museum,' ii., 1841) pointed out the existence of three 

 pairs of apertures opening into the branchial sac, besides the genital 

 and anal openings ; and he affirms that they open into as many 

 closed sacs, which communicate neither with one another nor with 

 the cavity that contains the heart. M. Valenciennes indicates the 

 difference in the structure of the anterior and posterior venous 

 appendages. He seems to me to have seen something of the part 

 which I have described as the pallio-visceral ligament ; but I cannot 

 clearly comprehend either his figure or his description. 



Van der Hoeven, in his ' Contributions to the Knowledge of 

 the Animal o£ Nautilus pompilius,^ 1850, confirmed the statement 



