Many of the butterflies of India were given their English common names by Charles Bingham, a career military officer in British India, who took up entomology as a very serious hobby after being posted to Burma in 1877. The butterfly genera called Lascars and Sailers were given their English common names by him, in the idiosyncratic manner of the 19th century British in India. Eastern Indian sailors on British vessels were called lascars; the names throw light on British society of that time.
The common lascar (Pantoporia hordonia), one of which you see in the featured photo, was described in 1790. But a common name was given by Bingham in his books on the butterflies of India, published in 1905 and 1907, when he settled in England after his retirement. The sullied sailer (Neptis clinia), which you see in the photo below, has the same overall shape and markings, albeit in different colours.
The sailers and lascars were very common in early April in the Hollongapar forest. They flew at about shoulder and head height. Their flight is weak; every flap of the wing is followed by an interval of gliding, and they easily alight on a sunny leaf, or descend to the ground. Still, they fly up very quickly when they are disturbed.
I used the common names for the whole genus, because there are several species of each, distinguished by slightly different wing markings. You can see a whole lot of similar looking species in the web pages for Neptis, Pantoporia and Phaedyma in the IFoundButterflies web site. You find them all over India, and once upon a time I’d managed to chase down a fair fraction of them. In April I was happy to photograph just the two you see here.