ON THE BENO-PEEICARDIAL CANALS IN PATELLA. 325 



injection being forced through weak spots where the kidneys 

 reached the wall of the pericardium. In conclusion, von 

 Erlanger stated that in Patella there is '^ no reno-pericardiac 

 duct whatever." 



The absence of the communicating canals seemed now to be 

 as firmly established as their presence had appeared to be but a 

 short time before. The matter was not long allowed to rest in 

 this condition. Hardly had naturalists become reconciled to 

 V. Erlanger's view, when Dr. Bela Haller published some elabo- 

 rate studies on Prosobranchs (ISO-l-, Haller), in which he 

 describes in considerable detail a right reno-pericardial canal in 

 Patella magellanica. A dissection is figured showing the 

 apertures of this canal. As for the left canal, Haller denies its 

 existence : " Wie wir wissen, hat Cunningham auch fiir die linke 

 Niere eine pericardiale Miindung behauptet, darum war ich, 

 obgleich dieses mir nach dem Verhalten bei der Monobranchen 

 hochst unwahrsheinlich vorkam, doch bemiiht dieses unbe- 

 fungen zu verfolgen. Auf Totalpraparaten war dieses in Folge 

 der Rubtilen Verhaltnisse nicht recht moglich und darum 

 beniitzte ich hiefiir raeine Querschnittserien, doch konnte ich 

 bei keiner der untersuchten Formen eine Miindung der linken 

 Niere in das Pericard auffinden. Eine solche fehlt ganz ent- 

 schieden.^' 



Having thus briefly reviewed the history of the subject, I 

 must now give a short account of my own observations, which 

 are founded on the examination of complete series of transverse 

 sections. The structure and relations of the small left and 

 large right kidney are now so well known that they need not 

 again be mentioned. I shall, therefore, merely describe the 

 selected sections figured on PL 24. 



In fig. 1 is represented a section through the two kidneys, 

 rectum, and pericardium, some little way behind the posterior 

 limit of the mantle chamber. It will be seen that from the 

 right ventral corner of the pericardium proceeds a diverticulum, 

 which, in fact, is the beginning of the right reno-pericardial 

 canal. A section taken farther forward (fig. 2), so as just to 

 cut through the hinder region of the mantle cavity, shows the 



VOL. 41, PART 2. NEW SERIES. Z 



