Complex sentence: With the exception of the Koshare each was a kachinam or personification of a spirit; it was believed that when a member of a kiva dons the mask of a kachinam he abandoned his personality and became possessed by the spirit.
Split into simpler sentences: With the exception of the Koshare, each was a "kachinam" or personification of a spirit. It was believed that when a member of a kiva dons the mask of a kachinam, he abandoned his personality and became possessed by the spirit.