684 



MB. J. GBABLA.M KEE.B Olf THE 



[June 18, 



(4) The traces of metamerism exhibited by the heart in some 

 forms, there existing several pairs (four in Chiton magni- 

 ficus) of aurieulo-ventricular openings. 



(5) General relations of eoelom, nephridia, &c. 



(6) Eggs developed within follicles. 



Diagram showing the relationships of the eoelom and nephridia in 

 Amphinmira and Cephalopoda. 



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



gc, genital division of the eoelom ; pc, pericardiac division of the eoelom ; 

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

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

 seen still in communication with the rest of the nephridia. 



In regard to (5), fig. 6 indicates diagrammatically the relation- 

 ships of the parts concerned. In the case of Chiton (B) two 

 coelomic chambers are shown, one lying in front of the other — the 

 genital eoelom and the pericardium. The pericardium communicates 

 with the exterior by a pair of functional nephridia ; the genital 

 cceJom by the pair of genital ducts which from their relations can 

 hardly be otherwise than morphologically a pair of nephridia too. In 

 Chcetoderma (A), a less primitive animal, a less primitive arrange- 

 ment has been developed : the genital division of the eoelom has 

 developed a communication with the pericardium through which 

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



