English: Diagram of the two renal organs (nephridia), to show their relation to the rectum and to the pericardium. (Lankester.)

f, Papilla of the larger nephridium.

g, Anal papilla with rectum leading from it.

h, Papilla of the smaller nephridium, which is only represented by dotted outlines.

l, Pericardium indicated by a dotted outline—at its right side are seen the two reno-pericardial pores.

ff, The sub-anal tract of the large nephridium given off near its papilla and seen through the unshaded smaller nephridium.

ks.a, Anterior superior lobe of the large nephridium.

ks.l, Left lobe of same.

ks.p, Posterior lobe of same.

ks.i, Inferior sub-visceral lobe of same.