Page:Eurypterids of the Devonian Holland Quarry Shale of Ohio.djvu/8

 of integument retaining typical Pterygotus ornamentation probably belong to this species, although part may be referable to the rarer Pterygotus (Erettopterus) serratus (see p. 87). The species is based on three incomplete chelicerae, the gnathobases of two coxae, a metastoma, and a pretelson. Fragments described herein indicate a form that reached an overall length of body, exclusive of the long chelicerae, of more than five feet, a size not unusually large for the genus.

The holotype (PE5105) comprises fragments of an articulated chelicera retaining the proximal part of both rami (see fig. 35). Two of the specimens designated as paratypes (PE5106 and PE5107) retain the base and ramus of the chelicera, as well as parts of the fixed and free rami (see figs. 36 and 37). A reconstruction of an almost complete chelicera is therefore possible (see fig. 38).

The hand of the chelicera comprises a rather slender, rectangular structure, without any trace of ornamentation. The rami are slender, and the free ramus is slightly more curved. The distal ends are missing in our specimens. On the inner edge of the rami are a number of teeth, all of which are curved backward and are stout and unusually short. Part of this general stoutness of the teeth is due to conspicuous wearing, as the distal part of each tooth has been rounded off as if by an abrasive. However, part of the general stout aspect is inherent. The majority of the teeth are small, with several large, thick teeth interspersed. The central, or principal, tooth of the free ramus (no. 1 in figs. 35–38) is the largest, and is represented by a curved, thick structure. Nearly opposite this tooth is a similar but smaller tooth (no. 3). In front of this tooth is another one, half as large (no. 4). This combination is present on all chelicerae of this species.

Each tooth is longitudinally marked by narrow ridges, which generally are described in the literature as striations, anastomosing furrows, or fine longitudinal furrows. In reality, these structures are longitudinal ridges strengthening the individual tooth and are not furrows or striations. The longitudinal ridges are worn off at the distal end of most teeth in the present specimens.

The hand of specimen PE5107 measures 18.5 mm. at midsection; the large tooth (no. 3) is 3 mm. long by 2.2 mm. wide; the ramus, opposite the no. 3 tooth, is 6.3 mm. wide. In the holotype (PE5105) the free ramus opposite the no. 1 tooth is 14.5 mm. in diameter, and the principal tooth, which has been broken out, measures 9.1 mm. in length and 6.3 mm. at the base. Paratype no. PE5106 is approximately the same size as paratype PE5107.