Page:A Revision of the Families and Genera of the Stylonuracea (Eurypterida).djvu/9

 Descriptions of all families and genera of the Stylonuracea are included here, as well as lists of the species referred to each genus. The families included are: Dolichopteridae, Stylonuridae, Pageidae, Drepanopteridae, Kokomopteridae, Rhenopteridae, Laurieipteridae, Woodwardopteridae, and Hibbertopteridae.

Diagnosis.—Dolichopteridae of medium size; test apparently smooth except for circular scales on certain appendages; prosoma subquadrate; lateral eyes situated close to anterolateral angles; ocelli centrally located; ventral doublure unknown; chelicera unknown, probably small, simple; second to fourth paired appendages stout, increasing in length posteriorly, spinous; fifth and sixth paired appendages with supplementary flat lobes on distal joints, ultimate joint forming a large claw in the fifth, and a broad, greatly enlarged lobe (paddle) in the sixth appendage, lateral margin of paddle slightly serrate; metastoma narrow, cordate anteriorly, truncated at base; male median appendage very long, two-jointed; female appendage very small, not well known; no appreciable contraction of metasoma; posterior tergites produced into wing-like epimera; telson spike-like (Kjellesvig-Waering and Størmer, 1952, p. 660).

Type species.—Eurypterus (Dolichopterus) macrocheirus Hall, 1859.

Distribution.—New York, Pennsylvania, Ohio, Saaremaa (Oesel), U.S.S.R., and England.

Stratigraphic range.—Ordovician to Devonian.

The following species are recognized for this genus: