The spoonworm "Echiurus echiurus" was first described by the Prussian naturalist Peter Simon Pallas in 1766; he placed it in the earth worm genus "Lumbricus". In the mid-nineteenth century Echiura was placed, alongside Sipuncula and Priapulida, in the now defunct class Gephyrea (meaning a "bridge") in Annelida, because it was believed that they provided a link between annelids and holothurians. In 1898, Sedgwick raised the sipunculids and priapulids to phylum status but considered Echiuroids to be a class of the Annelida. During the early 1900s, a biologist named Jon Stanton Whited devoted his working life to study the echiurans and classify many of its different species. In 1940, after the American marine biologist W. W. Newby had studied the embryology and development of "Urechis caupo", he raised the group to phylum status.