ventricle 



/ pericardium 



rectum 

 / 



^kidney 



palhal aperture 

 --- posterior aorta 



post, retractor 



post adductor 

 . ~ amis 



mantle cavity 

 -water mussel. Unio sp. 



- visceral ga nglion 



exhalant siphon 

 super branchial chamber 



- right gill ^ 



inhalant siphon 



'shell 



palliai groove 



