i8 95 . 



IN THE HOME OF THE NAUTILUS. 



4*3 



and dividing into two shortly before reaching the osphradium of 

 Lankester and Bourne, to which I am confident of having traced a 

 small nerve, arising from the point of bifurcation. The inner 

 and smaller visceral nerve passes over the region of the renal 

 sacs on each side to the base of what I may call the posterior 

 osphradia (os 2 ), to which it undoubtedly sends nerve-fibres, although 

 I cannot say positively that I have definitely traced these. In the 



Fig. 2. Dissection of the Pallial cavity of Nautilus pompilius. 



/. Funnel, b. Bristle passed into aperture of left rudimentary genital duct. 

 p. Male genital aperture, a. Anus. m. Mantle reflected back. m 1 . Muscular 

 margin of mantle. n l ,n 2 . Visceral nerves showing through the skin, b^.br 2 - The 

 branchiae, v 1 ^ 2 . Branchial veins, r 1 ,^. Region of anterior and posterior renal sacs. 

 The excretory granules with which the latter are usually filled produce a brilliant 

 vermilion colour in the fresh condition, os 1 ^^. Osphradia. 



N.B. — os 2 = post-anal papilla ; in this example its two component papillas were 

 separated by an interval of 2i millimetres. A line drawn from the anterior renal 

 opening to the posterior osphradium (os' 2 ) will pass over the posterior renal opening. 

 The inner and larger of the two posterior openings on each side is the viscero- 

 pericardial aperture. 



female, I have followed the main trunk of this nerve through the 

 nidamental gland. The two visceral nerves on each side arise close 

 together from the visceral ganglion 10 (posterior subcesophageal 

 ganglion of Owen). 



Finally, one can see from the accompanying figure that the two 

 papillae, discussed above, have essentially the same topographical 



As it crosses the renal sacs, the outer visceral nerve runs along the line 

 dividing the outer anterior sac from the inner posterior sac. 



10 The figure of the visceral nerves given by Keferstein corresponds more to 

 what I have found than does that of Owen. 



