16 WALTER K. FISHER, 



is situated on the dorso- sinistral side of the rectum, on that part 

 which extends freely into the pallial cavity (L.K, in red) and opens 

 like the right, abruptly to the exterior. This opening is near the 

 anterior end of the kidney and is much smaller than the right ureter. 

 It does not form a papilla like the right. The dorsal wall of the left 

 kidney is also fenestrated. The extent of the cavity is best shown 

 by Figs. 26 and F. Although the two kidneys approach each other 

 very closely over the rectum, so close indeed that the acini seem to 

 interdigitate in some places, I have been unable to find an actual 

 connection between the cavities of the two. 



The left nephridum, as well as the right, is actively excretory, 

 and the epithelial linings of the two are identical. The epithelium 

 is columnar to cubical, according apparently as it is situated over a 

 highly vascular area, or over one with little blood, as for instance the 

 muscular outer wall of the body (shell muscle). A large part of the 

 epithelium is what is usually called low columnar. The cells which 

 have roundish or oval nuclei are not very definite of outline, and are 

 clogged with fine granular matter, and often with bodies about half 

 as large as the nuclei. This granular matter, together with the larger 

 transparent bodies, is found thickly packed among the fine cilia with 

 which the epithelium is beset, in such a manner as usually to obscure 

 the cilia. Such excreted matter, as seen in sections, is undoubtedly 

 the decolorized greenish material which stains the kidney during the 

 life of the animal. The epithelium of the left kidney is as active as 

 that of the right and there is considerable of a blood supply con- 

 sidering the diminutive size of the organ. 



The reno-pericardial canals. In Lottia gigantea both 

 nephridia are in communication with the pericardium. This agrees 

 with what Goodrich x ) and Pelseneer 2 ) have found in other species 

 of the Docoglossa. (Compare Fig. F with Pelseneer's fig. 100, 1. c, 

 tab. 11.) 



The reno-pericardial canals are not short and to be seen in a 

 single transverse section, but are long and lie in several planes, and 

 are rather difficult to follow throughout their whole length. By 

 means of an injection of ink in one specimen, and the fortunate 



1) Edwin S. Goodrich, On the reno-pericardial canals in Patella, 

 in: Quart. J. microsc. Sc, V. 41, 1898, p. 323. 



2) Paul Pelseneer, Recherches morphologiques et phylogenetiques 

 sur les Mollusques archa'iques, Bruxelles 1899. 



