While we do not have records of where the emigrants on board specifically came from for the voyage of 1864-1885 of the Clarence, we do have some description of where emigrants come from on similar voyages. The Clarence was transporting emigrants from Bengal to the West Indies and Trinidad from 1860-1862.
The first voyage began the 3rd of November 1860 and concluded on the 22nd of January 1861 for a total of 81 days at sea. There were 376 emigrants on board, with 13 deaths (3.45% death rate.) Emigrants on this voyage were recruited from:Bengal, Behar, Orissa, The north-western provinces, Nepaul, Gwalion, Fyzabad, Lucknow, Lahore and Oude. The second voyage of the Clarence during this time began the 18th of December 1861 and concluded on the 4th of March for a total of 77 days at sea. There was a total of 462 emigrants on board having been recruited from:Bengal, Behar, Orissa, The north-western provinces, Gwalior, Kotah, Lahore, Punjab, Lucknow, Putyalah, Napual, Oude and Tirhoot.
Data presented by Lance Brennan et al. lends itself to mapping - here we show the major districts of origin of all Indian indentured laborers departing from Calcutta between 1844 and 1864: