MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 145 



tubules increase in size toward the ultimate branches. They are lined by a single layer of not very 

 tall columnar cells, the nuclei of which stained deeply while the body of the cells remained 

 unstained and clear. That the cells are secretory is proved by the fact that the cavities of the 

 glands were tilled by a secretion, the granules of which were so fine that it appeared homogeneous 

 under ordinary high powers. 



These glands may be the homologues of the glands Kerr described as being scattered over the 

 area between the preanal papillae and the nidamental gland in the female. I find the same area 

 continuously glandular and much thickened. (See p. 147.) 



The epithelium had been entirely rubbed off from the surface of the interbranchial papillae 

 and the preanal papillae, of which I made series of sections. Therefore. I have no personal 

 knowledge of its character. As regards the innervation of the papillae, serial sections do not 

 reveal any such abundance of nerves as we should expect, were they sensory organs of importance. 

 The edge of the ventral part of the mantle possesses a remarkable number of nerves, many of 

 considerable size. This being the fact, we have a right to expect that the innervation of sense 

 organs of the importance of osphradia will have an at least equally plentiful supply of nerves. 

 Instead of this being the case, serial sections do not show any nerves whatever passing into the 

 interbranchial or preanal papillae. The large nerve of the posterior gill is seen running by the 

 base of the interbranchial papilla, but neither in dissections nor in serial sections have I seen any 

 nerve pass from this into the papilla. 



I do not wish to be understood to deny that the interbranchial and preanal papillae are 

 osphradia. but I do wish to call attention to the fact that they are not yet proven to be 

 osphradia. Willey admits, and calls attention to the fact, that he has not been able to absolutely 

 trace any nerves into these papillae. He goes very much farther than the known facts warrant 

 when he regards the presence of vibratile cilia "as the final proof of the osphradial character of 

 the postanal papilla'."" While it is true that sensory organs are frequently covered by a ciliated 

 epithelium, among the cells of which the special sensory elements are nestled, the fact that certain 

 portions of the body of an animal are ciliated does not in and of itself constitute proof that these 

 portions of the body are sensory organs. The final proof as to whether or not these papillae of 

 Nautilus are osphradia must be, besides the presence of special sensory cells, their innervation; 

 and at present both these points are very much in doubt. The nature of the nerves of Nautilus, 

 to which Willey has called attention, and the position of these papilla? with respect to the course 

 of the nerves, render an investigation of their innervation quite difficult. 



The morphological importance of osphradia is too great to permit of any assumption of 

 their presence in Nautilus without complete proof. It is because I do not consider that the 

 osphradial nature of the papilla? under discussion has been proved beyond an}' doubt that I have 

 used the name "interbranchial papilla?" for the papillae which have been called the osphradia of 

 Nautilus ever since the publication of the paper by Lankester and Bourne. This is suggested 

 as a provisional name until such time as the true nature of these papillae shall have been proven. 



RENAL AND PERICARDIAL PORES. 



The renal organs are situated in the posterior portion of the mantle fold, their presence 

 causing the considerable thickness of this portion of the mantle. The glands situated upon the 

 anterior branchial arteries are shoved together in the median line below or anterior to the rectum. 

 The glands situated upon the posterior branchial arteries are just outside and behind those already 

 mentioned. So that we can with justice speak of anterior and posterior renal organs (Fig. 36). 

 The anterior renal sacs lie beside each other on either side of the middle line; the posterior renal 

 sacs are separated by the two anterior renal sacs. Each renal sac communicates with the exterior 

 by a slit-like opening situated upon the inner side of the mantle. The openings of the posterior 

 renal sacs are at the inner ends of the bases of the posterior gills (Fig. 3, R P). The openings 

 of the anterior renal sacs are located at the inner ends of the bases of the anterior gills, or near 

 where the anterior branchial veins pass through the mantle into the body (Fig. 3, R A). Upon 

 the inner side of each anterior renal pore is another opening, the pericardial pore (Fig. 3, P P). 



