Coat of arms of Maskelyne

The blazon

sa. a fesse, engr. or, betw. three escallops ar. — Crest, a demi lion, rampant, holding betw. his paws an escallop, [Borne hy the Rev. Nevil Maskelyne, D.D. F.R.S. forty-six years Astronomer-Royal, died, at Greenwich, Qth February, 1811, aged 79.]

A blazon is the description of a coat of arms in the technical language of heraldry. The drawing comes from that text, and from nothing else.