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Show 666 MR. J. GRAHAM KERR ON THE [June 18, The true ccelom (viscero-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 ccelom 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 Fig. 1. Sagittal section through Nautilus. Diagrammatic sagittal section through the animal of a young female of Nautilus pompilius, to show the general relations of the ccelom and ha?moccel. (The section really passes very slightly to the right of the mesial plane, so as to traverse one of the renal chambers.) haem, hsemoccel; g.c, genital division of the ccelom; p.c, pericardial division of the ccelom; a, aperture in septum dividing g.c from p.c; Je, 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 membranous bag which limits the cavity of the hsemoccel. The ccelomic 1 Pelseneer, op. cit. p. 192, says that the ccelom "s'etend dorsalement, autour de l'estomac, jusque vers la moitie de l'cesophage. II contient, outre la cceur, la glande genitale, la veine cave et un partie des appendices glandulaires des vaisseaux branchiaux afferents,"-a statement which is obviously at variance with the account here given in two important respects. |