Complex sentence: He joined the British Association for the Advancement of Science in 1832, a member of the Society of Entomologists of London in 1834 and the Geological Society of London in 1835.
Split into simpler sentences: He joined the British Association for the Advancement of Science (B.A.A.S.) in 1832 He became a member of the Society of Entomologists of London in 1834. He became a Member of the Geological Society of London in 1835.