1. 
   opisthobranchiata
   <zoology> A division of gastropod Mollusca, in which the breathing organs are usually situated behind the heart. It includes the tectibranchs and nudibranchs. ... Origin: NL, from Gr. Behind + gills. ... Source: Websters Dictionary ... (01 Mar 1998) ...
   Found op http://www.mondofacto.com/facts/dictionary?opisthobranchiata
   
   
2. 
   Opisthobranchiata
   • (n. pl.) A division of gastropod Mollusca, in which the breathing organs are usually situated behind the heart. It includes the tectibranchs and nudibranchs.
   Found op http://thinkexist.com/dictionary/meaning/opisthobranchiata/
   
   

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