49 



A RENO-PERICAEDIAC PORE IN AMPULLARIA URCEUS, Mull. 



By E. H. Btone, B.A., 

 Assistant in the Museum of the Eoyal College of Surgeons of England. 



Read lith January, 1898. 



Dk. von Eelangee, in the course of a criticism ' of Bouvier's account 

 of the renal organs of Ampullaria,^ uses these words : — " It seems 

 highly improbable to me that the lamellar renal organ should have 

 no communication with the pericardium. . . . This point and the 

 communication of the two renal organs ought certainly to be re- 

 investigated in well-preserved specimens by the method of sections." 



The following note, which is the result of the dissection of two 

 specimens of Ampullaria urcetis, Miill., and the examination of sections 

 cut from fragments of another,^ responds to a certain extent to this 

 expressed wish, although I should have been better satisfied if the 

 material at my disposal for section-cutting had been slightly more 

 abundant. 



As regards the general anatomy of the renal organs, I may say at 

 once that I have found Bouvier's description perfectly accurate, and 

 hence need only abstract enough from his account to make my own 

 addition intelligible. 



The kidneys of Ampullaria (see Figure) are two in number. One, 

 situated towards the right side of the body, close behind the portion 

 of the gill that lies nearest the heart, is triangular in shape, with 

 the base directed backwards to the left, and the apex forwards with 

 an inclination to the right {l.r.). The interior of this triangular right 

 kidney is occupied by a series of lamellae disposed at right angles 

 to its longer axis (hence the name "lamellar renal organ"); it 

 communicates with the exterior by means of a large slit-Kke opening 

 (r.o.), and with the second kidney by a much smaller one (i.r.o.), 

 though even this exceeds 1 mm. in length. The second kidney is 

 situated behind and to the left of the first, and is bounded in front 

 by the pericardium. It is a capacious chamber, with no external 

 outlet except through the right kidney ; the roof {v.r.) is thick and 

 extremely vascular, while the floor is so thin that the intestine {int.) 

 and other organs covered by it appear to project freely into the renal 

 cavity. Both kidneys are functional excretory organs, and each is 



> Erknger, "On the Paired Nephridia of Prosobranchs," etc.: Quart. Journ. 

 Micro. Sci., vol.,xxxiii (1892), p. 608. 



^ Bouvier, "Etude sur 1' Organisation des Ampullaires " : Mem. Soc. Philom. 

 (1888), p. 63*. 



^ These specimens are the property of the Eoyal College of Surgeons. The 

 dissection of the renal organs is No. 1,176, D, Phys. Series, in the Museum of that 

 Institution. 



VOL. III. — APRIL, 1898. 4 



