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XXVII. On the Structure and Homologies of the Renal Organ in the Nudibranchiate 
Mollusca. By ALBANY HANCOCK, F.L.S. 
(Plates LIV.-LIX.) 
Read June 2nd, 1864. 
Ina paper “On the Anatomy of Doris," by Dr. Embleton and myself*, we described 
what we took to be a portal heart, a peculiar pyriform vesicle situated directly below the 
pericardium, and opening into it. For reasons stated at the time, we believed that this 
organ threw venous blood into the liver. My confidence, however, in the accuracy of 
this determination was much shaken on not finding any similar organ or anything equi- 
valent to a portal system in the Cephalopoda, the study of the anatomy of which has for 
some time past engaged my attention. Had Doris really possessed a portal system such 
as we described, surely the more highly organized Cuttlefish should not be deficient in 
this respect. In the one case or the other it appeared to me that we must be in error. 
It therefore became necessary to re-examine this point in the Doridide, and in fact to 
institute in the Nudibranchs generally a more minute investigation than had hitherto 
been made of the renal organ, with which the so-called portal heart is connected. 
With this view I have now completed a rather laborious examination of a large collec- 
tion of Madras Nudibranchs kindly placed at my disposal by Walter Elliot, Esq., of 
Wolfelee, North Britain, and which form the subject of a recent communication to the 
Zoological Society by Mr. Alder and myself f. Some very interesting modifications of 
these organs have come to light during this investigation; and it is proposed on the 
present occasion to give a detailed account of them, and to take into consideration the 
bearing they have upon the question of the existence of a water-system in these animals, 
and also to examine their homological relation to the similar organs in some other 
Mollusks, particularly those in the Cephalopods. 
In the first instance, however, it is desirable to describe these parts in two or three 
British Dorides, especially as we had to some extent misunderstood in them the true 
nature of these organs, and there will thus be afforded an opportunity of correcting one 
or two errors that occur in our paper before “alluded to, the most important of which 
relates to the pyriform vesicle, which, as already stated, we described as a portal heart. 
The vesicle is essentially a portion of the renal organ; it is not related to the Hiver 8 
the way we supposed; and I am glad of being able on this occasion to correct a mistake 
Which we made, not from carelessness, but after a lengthened and painstaking investiga- 
tion of the subject. No doubt can exist of the fact as now determined, not only in our 
British species, but in large exotic specimens and yarious generic forms in which this 
organ presents numeróus and instructive modifications. In the British species, indeed, 
this subject is fraught with much difficulty, as well on account of their diminutive size as 
* Phil. Trans. for 1852 (pt. 1), p. 207. + Trans. of the Zool. Soc. vol. v. p. 113. 
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