ON THE ANATOMY OF NAUTILUS POMPILIUS. 



209 



been developed: the genital division of the coelom has developed 

 a communication with the pericardium through which the 

 genital products pass— and it has lost its original genital ducts. 

 Fig. C shows the condition in Nautilus, where again the same 

 two coelomic chambers are visible. Here also a communication 



Fig. 6. 



-gn 



Diagram showing the relationships of the coelom and nephridia in 

 Amphineura and Cephalopoda. 



A, Chatoderma; B, Chiton; C, Nautilus; D, Sepia. 



go, genital division of the ccelom; pc, pericardiac division of the coelom; 

 gn, nephridia of genital segment ; pn, nephridia of pericardiac segment ; 

 ks, kidney-sacs in Nautilus; in Sepia the two posterior kidney-sacs are 

 seen still in communication with the rest of the nephridia. 



has become formed between the two, but the two pairs of ducts 

 to the exterior still persist — the anterior nephridium here still 

 preserving its excretory portion — a more primitive condition 

 than in Chiton, and probably to be correlated with the fact of its 

 having become shut off from the main lumen of the duct. A 

 few irregular apertures in the wall separating the two coelomic 



