Page:Eurypterids of the Devonian Holland Quarry Shale of Ohio.djvu/20

 {| width="700px" align="center" . 50. Reconstruction of prosoma of Syntomopterus richardsoni, n. sp., drawn mainly from holotype, PE5120; ✕ 2. A: Ventral side of marginal rim of doublure. The large elongated pustules are on the dorsal shield, seen from the inside. B, C: Dorsal side of marginal rim. . 51. Diagram of prosoma of Syntomopterus richardsoni, n. sp., to show general direction of axis of elongated pustules, forming flow of ornament pattern. Prosoma restored to approximate natural dimensions.
 * Eurypterids of the Devonian Holland Quarry Shale of Ohio figure 50.jpg
 * Eurypterids of the Devonian Holland Quarry Shale of Ohio figure 50.jpg
 * Eurypterids of the Devonian Holland Quarry Shale of Ohio figure 51.jpg
 * Eurypterids of the Devonian Holland Quarry Shale of Ohio figure 51.jpg
 * Eurypterids of the Devonian Holland Quarry Shale of Ohio figure 51.jpg
 * Eurypterids of the Devonian Holland Quarry Shale of Ohio figure 51.jpg
 * }

wart-like, round pustules of various sizes. Anteriorly, toward the marginal rim, these pustules are slightly elongated, and around the marginal rim they become more elongated, or elliptical (see fig. 50, A), grading into pointed, elongated scales in the region of the genal angles. This results in a "flow-like" pattern from a point anterior to the lateral eyes, around both sides of the prosoma to the genal angles (see fig. 51), a pattern which is characteristic of many Stylonuridae such as Ctenopterus, Melbournopterus, Stylonurus, and Tarsopterella, and which accentuates the double "pouch-like" structures of the prosoma in these genera.

The ornamentation of the marginal rim, however, contrasts greatly with that present on the rest of the carapace. Here the pattern is