TRANSVERSE SECTIONS 



101 



kidneys, immediatGly below the pericardium. 

 They are separated from each other in the median 

 plane by the vena cava. 



Fia. 28. — Anodonta cygnea. Transverse section of the animal passing 

 through the middle of the length of the ventricle. The cavity of 

 the heart is dotted, (a. m. ii.) 



A, sliell. AT7, left auricle. B, ligament. BC, branchial cavity. 

 P, foot. I, intestine. IG-, left inner gill. K, left kidney. KO, Keber'a 

 organ of the right side. XiM, left xaantle-lobe. OG-, left outer gill. 

 PG, pericardial cavity. B, cavity of rectum. B.&, genital gland, ovary or 

 testis. "RM-t edge of right mantle-lobe. SC, supra-branchial canal of right 

 outer gill. T, typhloaole. IT, left ureter. V, wall of ventricle. V, cavity 

 of ventricle. VC, vena cava. W, suprar-branchial canal of left inner gilL 

 X) free upper edge of the inner lamella of the right inner gill : between this 

 edge and the body is the silt through which the branchial cavity communicates 

 with the supm-brauchial canal of the inner gijl, 7, the right cerebro-visoeral 

 connective. 



