The anatomy of Lottia gigantea Gray. 



17 



presence of gas in the canal of another, I was able to follow these 

 ducts quite to the papilla by gross dissection. The relations are 

 shown in Fig. 26. 



The canals are for the most part prolongations of the pericardium, 

 only that exceedingly small portion within and just adjacent to the 

 papilla (which marks the opening into each nephridium) is ciliated 

 and possesses a high epithelium (Fig. G). 



Fig. F. An oblique transverse section through portions of the right and left 

 kidneys, mantle cavity, gonad, and visceral mass of right side to show openings of reno- 

 pericardial canals and gonoduct. The gonoduct is actually somewhat in front of this 

 section. A. Ct. V afferent ctenidial vessel, Bl. V blood vessel, Ct ctenidium, Gn gonad, 

 Gn.D gonoduct, I intestine, L liver, L.K left kidney. L.R.P left reno-pericardial pore, 

 Ma. C mantle cavity, Ma. H mantle hood, Med. M median membrane of ctenidium, 

 Per pericardium, Rect rectum, R. K rectal portion of right kidney, R. K' sub-anal 

 portion of right kidney, R. R. P right reno-pericardial pore. 



The right posterior corner of the triangular pericardium narrows 

 down abruptly to a funnel-shaped opening directed toward the right 

 and slightly downward. This canal on reaching the rectum divides 

 into two branches, the left passing forward along the outer wall of 

 the left kidney to a short distance behind the left ureter, where it 

 opens into the nephridium by a tiny papilla, lined with high epithelial 

 cells beset with long cilia. The other branch of the pericardial pro- 

 longation dips down under the rectum , and comes to lie close 

 beneath the renal epithelium of the rectal, or upper, portion of 

 the right kidney. It then turns forward, parallel to the rectum, 

 and opens by a tiny papilla, with a ciliated lumen, near the ureter 

 (Fig. 26). 



Zool. Jahrb. XX. Abth. f. Morph. O 



