Narasimha Purana's68chapters include the narratives of the Yama Gita and the ten Avatars of Vishru.
The recension presented by the printed editions of the text has 68 chapters. The chapters 36-54 consist the narratives of the ten Avatars of Vishnu. The 8th chapter of the text is one of the three versions of the Yama Gita (other two versions are the Vishnu Purana, Book 3, ch.1-7 and the Agni Purana, Book 3, ch.381). 
