516 MR. A. HANCOCK ON THE STRUCTURE AND HOMOLOGIES OF THE 
drical in form, about as wide as long, with the ends flattened; it is strongly plicated 
in the interior, and has attached to it a tubular prolongation (Pl. LIV. fig. 5): but the 
character and extent of this appendage were not ascertained; and, indeed, several points 
in connexion with the renal organ in this form require a fuller examination than, on 
account of the deficiency of specimens, I have been able to give them. 
The first form in which we observe any marked change in this complicated apparatus 
is Hexabranchus gloriosus*. In this magnificent Nudibranch the renal chamber proper 
(Pl. LVI. fig. 1) is much reduced in size, and has assumed a tubular form of limited 
width, stretching almost from end to end of the liver, along the median dorsal line, 
parallel to and on the right side of the great branchio-hepatic vein. It tapers a little 
backwards to the external orifice (which is situated directly above the anal nipple), and is 
connected with the pyriform vesicle by a short wide tube. 
On laying this tubular chamber open (Pl. LVI. fig. 2), however, it is found not to 
be a simple tube, but to have numerous branches of various sizes passing from either 
side, which for the most part follow the trunk arteries that ramify over the surface of 
the liver, but their exact course and extent were not determined. Small orifices in the 
floor of the organ indicate that branches also dip into the substance of the liver. 
Immediately beneath the floor of the chamber, and bulging into it, is observed the 
tubular prolongation of the pyriform vesicle. It is almost as wide as the chamber itself, 
and, bending forward, stretches nearly as far as its anterior extremity, where the prolon- 
gation opens into it by a slit-like orifice. On laying this tube-like organ open (Pl. LVI. 
fig. 3), the inner surface is seen to be thickly studded all over with erect, firm, dendritic. 
tufts (fig. 4), which are coated, as well as the surface to which they are attached, with 
minute granular cells. 
In Plocamophorus Ceylonicus, one of the Polyceride, the renal organ undergoes a still 
more remarkable change (Pl. LV. fig. 5). In this species the narrow extremity of the 
pyriform vesicle gives off, as it were, two tubes of no great width. One (7), which 18 
the wider of the two, turns backward, and, after running for a little way in contact with 
the upper surface of the intestine, tapers as it terminates at the pore by the side of the 
anus: the walls of this tube are delicate and transparent. The other tube (J) extends 
down the left side of the liver, in a cleft dividing the anterior and posterior lobes. In its 
course it passes over the great branchio-hepatic vein, to the wall of which it is firmly 
adherent, and after running for a short way in contact with the intestine, which issues 
from the same cleft, it tapers gradually and terminates in a cecal extremity. Through- 
out its whole length it is lined with a yellowish glandular matter, which in places 
becomes broken up into irregular nodules. These two tubes are the sole representative 
of the renal chamber, which we have seen so extensively developed in some of the other 
forms. It has now assumed the character of a cecal gland with a tubular external 
outlet, which is in connexion with the pyriform vesicle. 
The lamin:e in the interior of the pyriform vesicle are very ample, but become abruptly 
curtailed as they approach the lower or pointed extremity of the organ; they are thence 
* This; i : 
This is the Doris gloriosa of Kelaart, in the Journal of the Ceylon Branch of the Royal Asiatic Society. 
