428 J- T. Ciinningham, Note on the structure and relations etc. 



Fig. 4. Section passing through external opening of kidney. Zeiss aa. 



eo external opening of kidney. 

 hl blood lacunae. 



hr origin of branchia. 



/i right hand fold to cover the shell. 



/2 left hand ditto. 



ep^ epithelium lining shell cavity. 



e^2 epithelium of the body surface between the left epipodiiim and the mantle. 



mu musculature. 

 Fig. 5. Sections of a trabecula containing a blood lacuna. Zeiss E. Oc 4. 



rep renal epithelium. 

 hl blood lacuna. 



hlc blood corpuscles. 

 Fig. 6. Section of a trabecula containing muscular fibres. Zeiss E. Oc. 4. 



rep renal epithelium. 



mu muscular fibres. 

 Fig. 7. From a fresh teased preparation of the renal tissue. Zeiss E. Oc. 4. 



a surface of the renal epithelium. 



h and c cells containing a crystal. 



ä cell containing crystal and irregulär concretion. 



e concretions escaped from cells. 



/ cell with protoplasm and nucleus (?) . 

 Fig. 8. Cells pressed from external opening of the renal organ. 



