BUEiSrE : EEWO-PEEICAEDIAC PORE IN AMPULLAEIA.. 



51 



the lamellar kidney of Ampullaria and the pericardium. This surmise, 

 as we have seen, is not borne out by the facts, so we must consider, 

 I suppose, on Erlanger's hypothesis, that the vascular and not the 

 lamellar kidney is the left, corresponding' to the left kidney of Dioto- 

 and Heterocards and to the only remaining kidney of Monotocards — 

 thus restoring Bouvier's original arrangement. But since this view 

 is opposed by the close similarity of structure between the lamellar 

 kidney of Ampullaria and the only kidney of Bythinia, we should 

 do well to pause before accepting it on the strength of the pore 

 alone, and more especially when we observe the peculiar position 

 of the pore. The pore, as already shown, is situated, not, as one 



Dissection of Ampullaria nrceus.- — The mantle has been reflected to the right, and 

 the renal organs and pericardium have been opened. 



aff.v. cut end of afferent vessel of posterior kidney, aff-v'. the corresponding vessel 

 in the reflected roof of the kidney, cff.v. the efiierent vessel of posterior kidney. 

 g. gill. h. heart within the pericardium, int. coils of intestine protruding 

 into cavity of posterior kidney, i.r.o. inter-renal opening. I. lung reflected 

 to the right, l.r. lamellar renal organ, op. operculum, p.p. pericardiac 

 process, re. rectum, r.o. opening from lamellar organ to exterior, r.pi.p. reno- 

 pericardiac pore. xi.r. vascular roof of posterior kidney reflected backwards. 



would expect, in the flat partition-wall between the kidney and the 

 pericardium, but towards the apex of a curious figure-like process 

 of the latter, that stretches across the cavity of the large vascular 

 kidney, and loses itself, after assuming the form of a solid cord, on 

 the margin of the inter-renal opening. Does not this dragging of 



