Ian Lockwood / Purple-Faced Langur (Trachypithecus vetulus) in a suburban evergreen forest environment. Endemic, Sri Lanka, Endangered species

Ch'ien Lee / Purple-faced Langur (Trachypithecus vetulus) mother and juvenile, Sinharaja Forest Reserve, Sri Lanka

Ernie Janes / Purple-faced leaf monkey (Semnopithecus vetulus) Sri Lanka.

Lucas Bustamante / Purple-faced langur (Trachypithecus vetulus) holding stick and looking up, Sinharaja, Southern Province, Sri Lanka.

Lucas Bustamante / Purple-faced langur (Trachypithecus vetulus) with wet fur, feeding, Sinharaja, Southern Province, Sri Lanka.

Robin Chittenden / Purple-faced langur (Trachypithecus vetulus) in tree, Sri Lanka.

Robin Chittenden / Purple-faced langur (Trachypithecus vetulus) on branch, Sri Lanka.

Lucas Bustamante / Purple-faced langur (Trachypithecus vetulus) eating on a branch. Sinharaja, Southern Province, Sri Lanka

Nick Garbutt / Purple-faced langur or leaf monkey (Trachypithecus vetulus) in forest canopy. Sinharaja National Park, Sri Lanka.

Anup Shah / Nilgiri langur (Presbytis johni) in tree. Anamalai Tiger Reserve, Western Ghats, Tamil Nadu, India.

Ernie Janes / Purple-faced leaf monkey (Trachypithecus vetulus) Sri Lanka, endemic, endangered species.

Ernie Janes / Purple-faced leaf monkey (Trachypithecus vetulus) Sri Lanka, endemic, endangered species.

Ernie Janes / Purple-faced leaf monkey (Trachypithecus vetulus) Sri Lanka, endemic, endangered species.

Kevin Schafer / Montane Purple-faced Langur / Bear Monkey, (Trachypithecus vetelus monticola) in canopy. Highlands near Nuwara Eliya, endemic to Sri Lanka.

Kevin Schafer / Montane Purple-faced Langur / Bear Monkey(Trachypithecus vetelus monticola) sitting in tree. Endangered species. Highlands near Nuwara Eliya, endemic to Sri Lanka.

Kevin Schafer / Montane Purple-faced Langur / Bear Monkey, (Trachypithecus vetelus monticola) sitting on log. Endangered species. Highlands near Nuwara Eliya, endemic to Sri Lanka.

Kevin Schafer / Purple-faced Langur (Trachypithecus vetulus) foraging, highlands near Nuwara Eliya, Sri Lanka

Kevin Schafer / Purple-faced Langur (Trachypithecus vetulus), highlands near Nuwara Eliya, Sri Lanka

Kevin Schafer / Purple-faced Langur (Trachypithecus vetulus) in tree, Sinharaja Biosphere Reserve, Sri Lanka

Kevin Schafer / Purple-faced Langur (Trachypithecus vetulus) in highlands near Nuwara Eliya, Sri Lanka

Chien Lee / Purple-faced Langur (Trachypithecus vetulus), Hakgala Botanical Garden, Nuwara Eliya, Sri Lanka

Chien Lee / Purple-faced Langur (Trachypithecus vetulus), Hakgala Botanical Garden, Nuwara Eliya, Sri Lanka

Fabio Liverani / Purple faced Langur monkey (Trachypithecus vetulus) sitting in tree, Horton Plane National Park, Sri Lanka

Ian Lockwood / Purple-faced langur (Trachypithecus vetulus) in a suburban evergreen forest environment. Endangered species, Sri Lanka

Ch'ien Lee / Purple-faced Langur (Trachypithecus vetulus) feeding in tea plantation, Sinharaja Forest Reserve, Sri Lanka

Ch'ien Lee / Purple-faced Langur (Trachypithecus vetulus) mother and juvenile, Sinharaja Forest Reserve, Sri Lanka

Ch'ien Lee / Purple-faced Langur (Trachypithecus vetulus), Sinharaja Forest Reserve, Sri Lanka

Sandesh Kadur / Purple-faced langur (Trachypithecus vetulus) Sri Lanka.