90 



THE FKESHWATER MUSSEL 



D. The Kidneys. 



The kidneys, or ' organs of Bojanus,' are paired, and lie 

 side by side just beneath the pericardium. 



PR 



K R U CO UO 



v' I L..B' 



LG 



SC LM 



FIG. 20. Anodonta cygnea. Diagrammatic view from the right side. 

 The right valve of the shell, the right mantle-lobe, the right gills, 

 and the right auricle, have been removed. The alimentary canal 

 has been laid open from the right side as far as the point where it 

 enters the pericardial cavity. The pericardial cavity, the ventricle, 

 and the right kidney and ureter have been laid open from the right 

 side. The longer arrow passes from the pericardial cavity through 

 the right reno-pericardial aperture into the right kidney. The 

 shorter arrow passes through the external aperture of the right 

 ureter. (A.M.M.) 



A, margin of the left valve of the shell in which the animal is lying. 

 AA, anterior adductor muscle. AN", anus. B, ligament of the shell. 

 BD, bile-duct. BD', openings of bile-ducts into stomach. C, cloacal 

 cavity. D, septum separating the cloacal from the branchial cavity. E, ten- 

 tacles bordering inhalent aperture. F, foot. G, line of fusion of inner 

 lamellae of right and left inner gills. GO, genital aperture. H, anterior 

 aorta. I, intestine. K; kidney. L, liver. LG, inner gill of left side. 

 LM, left mantle^obe. M, mouth. N", posterior aorta. O, oesophagus. 

 PA, posterior adductor muscle. PC, pericardial cavity. PK, right pos- 

 terior retractor muscle. B., rectum. BG, genital gland ovary or testis. 

 BM, line of attachment of right lobe of mantle. BP, right reno-pericardial 

 aperture. S, stomach. SC, median supra-branchial canal, lying above the 

 inner gills. T, typhlosole. TJ, right ureter. TTO, external opening of right 

 ureter. V, cavity of ventricle. 



