Stedman (273) kindly provides this definition and commentary –– with guidance from the OED (228): “This refers to the classical verse form, the elegiac, in which elegies (mournful verses) were written. The elegiac distich consisted of an hexameter and a pentameter, and the metre was dactylic. So it is appropriate for the major-general, because it is classical and also relatively difficult and abstruse; but I suppose he had a classics master at school who made him put things into elegiac verse!” Cameron (66) adds that setting a passage into Latin elegiacs was a standard exercise for English schoolboys. Dealing with the life and fate of Heliogabalus was no doubt considered a cautionary lesson. But press on.
I quote in elegiacs all the crimes of Heliogabalus