Section 9. No Kidney on the Vertebrate Pattern Is Found, but the

following structures have, among others, been suggested as renal organs:--

(a) Certain canals, the brown tubes of Lankester (b.t.L., Figure 2, Sheet 19), a pair of pigmented tubes opening into the atrium at the hind end of the pharynx, lying forward along by the dorsal coelomic canals, and having an internal opening also.

(b) Certain tubuli described by Weiss as situated in a series along the upper corners of the atrial cavity, and communicating, after the fashion, of the "nephridia" of the earthworm, with the coelom and with the exterior (or, rather, with that portion of the animal's exterior enclosed in by the atrial wall; compare Section 6).

(c) The general epithelial lining of the atrium.

The reproductive organs (Figure 4, Sheet 20, g.) are masses of cells situated in an isolated part of the coelom in the atrial folds, and, having no ducts, their contents must escape into the atrium by rupture of the body-wall. Thence they escape either by gill-slits, pharynx and mouth, or, more generally, through the atrial pore. The animals, like all the vertebrata, are dioecious, i.e., male or female.