No. 3.] THE ANATOMY OF NAUTILUS POMPILIUS. 155 



The nephridial and pericardial openings, the anus, osphradia, 

 and nidamental gland are also all upon the inner side of the 

 mantle. The only parts of the pallial complex which are situ- 

 ated upon the body wall are the openings of the reproductive 



organs. 



Thus there is in the Nautilus pompilius the same arrange- 

 ment of the parts of the pallial complex as in many Gastero- 

 poda. Opening in the median line upon the inner side of the 

 mantle is the anus. Symmetrically disposed upon either side 

 of the anus, also upon the inner side of the mantle, are the 

 pericardial and nephridial pores, gills, and osphradia. Within 

 the mantle, near its base, are the nephridia. The heart is 

 close to the base of the mantle, but not within it. The repro- 

 ductive openings, as in the Gasteropoda, are upon the body 

 wall, one at each side of the body. 



These relations of the parts of the pallial complex are very 

 evident in all my specimens (sixty-six in all), and must be very 

 much more distinct in living specimens, in which the mantle 

 has not been shrunken by reagents. From the manner in 

 which Huxley ('58) speaks of the positions of the nephridial 

 pores, I judge that he recognized the same relation of the parts 

 of the pallial complex which I have here. 



In none of the papers listed in the bibliography at the end 

 of this paper have I found mention of the points which I here 

 note, and which seem important enough to justify publication 

 in advance of a more extended account of the anatomy of 

 Nautilus. 



