52 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



the pericardium towards the lamellar kidney, first as a tube, then 

 as a solid cylinder, strongly suggest that the relation of the lamellar 

 kidney to the pericardium may at some time have been more intimate 

 than it is at present ? May not, for instance, the reno-pericardiac pore 

 have been originally situated in the lamellar kidney on a long diverti- 

 culum of the pericardium, and subsequently have undergone migration 

 into the vascular kidney, accompanied by ati'ophy of the distal portion 

 of the pericardiac process ? Or, perhaps, there may have been two 

 reno-pericardiac pores, one to each kidney, situated on a common 

 pericardiac diverticulum, of which that belonging to the lamellar 

 kidney has since been lost. However, apart from what may, or may 

 not, have been the case formerly, the present features of the pore 

 are sufficiently peculiar to warn one to be cautious in assigning too 

 great Aveight to it in any attempt to determine which kidney of 

 Ampullaria is the representative of the single kidney of other 

 Monotocards. 



