LINKS

http://hes.ucfsd.org/gclaypo/circdia.html

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/circulatory%20system/circulat.htm

http://circsystemsunsig09r3b.wikispaces.com/(e)%09+Comparing+human+circulation+system+with+other+species

http://infusion.allconet.org/webquest/PhylumMollusca.html