Edward Drinker Cope (1840–1897) reconstructed and named the type specimen of Elasmosaurus platyurus in 1869. In publishing this specimen, he made reference to various early 19^th century publications on plesiosaurs. Along with these publications, he would have had access to images of various fossil bones including vertebrae of ichthyosaurs and plesiosaurs which were printed in Edward Lhwyd's Lithophylacii Britannici Ichnographia (1699) as copies of the book were readily available to him in three Philadelphia research institutions. Cope did not refer to Lhwyd even though he had access to the book, and reasons for this are presented.