INCISUEA (sCISSURELLA) LYTTELTONENSTS. 13 



ratory. It is a triangulai* sac lying close alongside of the 

 rectum and projecting largely into the pericardium. It opens 

 into the mantle-cavity by a simple slit-shaped aperture with 

 somewhat tumid lips (fig. 9). The majority of the specimens 

 of which I cut sections were females, and in all of them the 

 cavity of the sac was large and but slightly broken up by 

 ridges or papillae projecting into it. In all the specimens the 

 epithelium lining the cavity of the sac and covering the 

 papillas had the characters shown in fig. 14. The cells are 

 large and pale, with pale nuclei, and most of them are stuffed 

 with rod-shaped masses which stain very deeply with iron 

 hjematoxylin. Whatever may be the nature of these rods, 

 which, as shown in the figure, have rhomboid outlines and 

 are appai'ently crystalline, they have clearly been taken up by 

 the amoeboid cells of the left kidney from the adjoining blood- 

 spaces, for these latter are also filled with similar rods, which, 

 however, are smaller, more transparent, and stain less deeply 

 in hgematoxylin. The left kidney differs considerably in appear- 

 ance according to its functional activity. In some specimens 

 no rod-shaped bodies can be detected in the cells, and the 

 walls of the kidney sac then appear pale and thin. In other 

 specimens, again, no rod-shaped bodies can be seen in the 

 blood-sinuses, but the kidne^^-cells are stuffed so full of them 

 that their outlines are no longer distinguishable. In other 

 specimens, again, the rod-shaped bodies are abundant in the 

 blood-sinuses and more or fewer are present in the kidney- 

 cells. A portion of the epithelium of a specimen in the last 

 condition is represented in fig. 14. The fact that the histo- 

 logical character of the left kidney or papillary sac in Haliotis 

 and Trochus is different fi-om that of the right kidney was 

 established by Remy Pei-rier in his careful studies on the 

 kidneys of prosobranch Gastropoda, and Pelseneer (11) after- 

 wards showed that the amoebocytes of the papillary sac take 

 up solid particles, such as carmine or Indian ink, injected 

 into the blood-sinuses, whereas the secretory cells of the right 

 kidney eliminate sulphindigotate of soda injected in solution 

 into the blood. Both kidneys of Patella are depuratory, that 



