The second edition of J. W. Dawson's Acadian Geology (1868) contains some notes communicated by C. F. Hartt. One of these, on p. 643, runs as follows:

“Eocystites primçvus, Billings, Coll. Hartt (Fig. 220). The little plate with radiating sculpture, represented somewhat enlarged in the figure, is regarded by Mr. Billings, to whom the specimens have been submitted, as indicating anew genus of Cystideans.”

In this perfunctory manner, without diagnosis or description, was the genus Eocystites founded. Since a named species was mentioned, that species, E. primçvus, must be taken as genotype, and the generic name is thereby validated.