TASK DEFINITION: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
PROBLEM: " Megasthenes lived with Sibyrtius , satrap of Arachosia , and often speaks of his visiting Sandracottus , the king of the Indians . "

SOLUTION: Arrian explains that Megasthenes lived in Arachosia , with the satrap Sibyrtius , from where he visited India : Megasthenes lived with Sibyrtius , satrap of Arachosia , and often speaks of his visiting Sandracottus , the king of the Indians . "

PROBLEM: An epicalyx , an additional whorl around the calyx of a single flower , is a modification of bracteoles .

SOLUTION: An epicalyx , which forms an additional whorl around the calyx of a single flower , is a modification of bracteoles In other words , the epicalyx is a " group of bracts resembling a calyx " or " bracteoles forming a whorl outer to the calyx " .

PROBLEM: Volcanic ash ( tephra ) has a geochemical fingerprint .

SOLUTION:
Tephrochronology is a method for geochemical correlation of unknown volcanic ash ( tephra ) to geochemically fingerprinted , dated tephra .