666 



MR. J. GRAHAM KERR ON THE 



[June 18, 



The true ccelom (yiscero-pericardial sac, Owen) has received 

 comparatively little attention from previous investigators, Grobben 

 and Lankester being the only authors who devote to it more than 

 a few passing words '. 



It is convenient to treat together the coelora itself, the excretory 

 and the genital organs as forming all parts of the same organic 

 complex. On reference to the diagrammatic longitudinal section 

 through the animal, it is seen that the ccelom is limited to the aboral 



Eig. 1. 



giz 



ml 



ov- 



haem 



Sagittal section through Nautilus. 



Diagrammatic sagittal section through the animal of a young female of Nautilus 

 pompUius, to show the general relations of the ccelom and hsemocoel. 

 (The section really passes Tery slightly to the right of the mesial plane, 

 so as to traverse one of the renal chambers.) 

 haem, hsemocoel ; g.o, genital division of the ccelom ; p.c, pericardial 

 division of the ccelom ; a, aperture in septum dividing g.c from p.c ; 

 k, right inner kidney-chamber ; r, pericardial gland corresponding to 

 this kidney-sac ; h, ventricle ; ov, ovary ; ph, crop ; giz, position of its 

 opening into the gizzard, which lies to the left of the plane of section ; 

 int, intestine ; v.c, vena cava. 



end of the body, where it forms a flattened space immediately 

 underlying the body-wall — between this latter and the thin mem- 

 branous bag which limits the cavity of the hsemocoel. The coelomic 



1 Pelseneer, op. cit. p. 192, says that the ccelom "s'^tend dorsalement, autour 

 de I'estomac, j usque vers la moitie de I'oesophage. II contient, outre la cceur, 

 la glande genitale, la veine cave et un partie des appendices glandulaires des 

 yaisseaux branchiaux afiKrents," — a statement which is obviously at variance 

 with the account here given in two important respects. 



