North American herpetology, or, A description of the reptiles inhabiting the United States /
^P HILADELPHM : J. DOBSON, CHESTNUT STREET. 1838. EMYS OREGONIENSIS.-Ifar/an. Plate I. Characters. Shell suboval, greatly depressed, serrated in front, slightly emarginate behind; sternum broad, oblong, serrated anteriorly, emarginate posteriorly, with a large black blotch extending to all the plates. Head small, elongated; upper jaw bidentate. Stnontme. Emys oregoniensis, Harlan, Amer. Jour, of Arts and Sciences, vol. xxxi. p. 382, plate 31. Description. The shell is suboval; broadest behind,
... ; broadest behind, and very slightly emarginate; anteriorly it is narrowed, and presents a serrated border; it is greatly depressed, almost flattened along the vertebral line. Of the five vertebral plates, the anterior is irregularly quadrilateral, with its two anterior angles very much prolonged, its lateral margin curved, and its posterior border convex and projecting; the second is hexagonal, with its anterior margin concave, to receive the posterior border of the anterior plate; the third and fourth are also hexagonal; the latter with its posterior margin concave; the fifth is heptagonal, its anterior margin shortest, roundest, and received into the concavity of the posterior margin of the fourth, and with its posterior border more extensive, and joined to four marginal plates. Of the lateral plates, the anterior is irregularly triangular, with its basis rounded, directed forwards, and joined to five of the marginal; the second and third are pentagonal; the fourth is nearly quadrilateral. The marginal plates are twenty-five in number, those in front being longest; the nuchal, or intermediate, is elongated, narrowed posteriorly, and projecting anteriorly; the first are quadrilateral, broadest behind, and serrated in front; the second and third are also Vol. II.-10 EMYSOREGONIENSIS. quadrilateral, and serrated anteriorly, but they are broadest in front. All these plates are marked with three concentric hnes posteriorly, and are longer than in any other species of Emys that has fallen under my observation. The fourth, fifth, sixth and seventh plates are quadrilateral, smaller, and revolute to form a small groove. The remaining plates are also quadrilateral, broader, but not revolute. The sternum is broad, slightly contracted in the middle, serrated in front, and emarginate behind. The gular plates are triangular in shape, vrith their bases directed forwards, and serrated; at their outer angles is a process, prominent, pointed, and projecting beyond the rest of the plate: between these two protuberances is a concavity for the neck. The brachial plr.tes are triangular, their bases round, their apices truncated and directed inwards; the thoracic are narrow, quadrilateral, with their posterior and external angles elongated; the abdominal are pentagonal, and very broad; the femoral are irregularly quadrilateral, and broadest externally; the subcaudal are rhomboidal. Of the supplementary plates, the axillary are triangular, with their apices turned backwards; the inguinal are larger and quadrilateral, with an anterior angle prolonged. The head is moderately large and elongated; the snout pointed. The upper jaw is furnished in front with two remarkable teeth, and the lower has a well developed hook. The anterior extremities are rather long, flattened, and covered with large transverse rows of scales; the fingers are five, palmated, and furnished with five strong nails. The posterior extremities are round at the thigh, but greatly flattened at the tarsus; the toes are five in number, and fully palmated, but only four are furnished with nails. The tail is lonor. Colour. The shell is dusky brown; the vertebral and lateral plates are marked by pale yellow lines; these communicate with each other, and give a reticulated appearance to the carapace; the marginal plates have each a similar vertical line EMYS O R E G O N I E N S I S. 11 subdividing them equally; the intermediate and two anterior on each side are mottled with pale yellow. The sternum is yellow, with a large black blotch in the centre, Avhich is very beautiful, as may be seen in the accompanying plate, but cannot be described; besides this, each brachial plate is marked in the centre with a small circular spot of black. The wings are black, marked with yellow; the under surface of the marginal plates is yellow, with a black spot, mottled with yellow, at the junction of each plate. The head is dusky above, with small pale yellow lines. The jaws are horn colour; a yellow line begins at the posterior and superior margin of the orbit, and runs along the lateral and superior border of the neck; another begins at the posterior and inferior margin of the orbit, and descends to join a third and still larger band that arises about the middle of the lower jaw; after the junction, they extend along the lateral and inferior margin of the neck. The throat is dark brown, with several longitudinal yellowish lines; one of these is remarkable-it begins at the chin, soon splits, and forms two larger lines; between these two is another and shorter line of the same colour. The anterior extremities are dark brown in front, with two longitudinal lines of pale yellow; one runs near the middle, the other along the superior margin: these lines are continued to the nails and to the webs, which are also yellow; the inferior surface is dusky. The posterior extremities are dusky above, irregularly marked with yellow; the convexity of the toes and the web being of the same colour. The tail is dusky above, with three yellow longitudinal lines; below, it is mottled with yellow. Dimensions. Length of shell, 7 inches 2 lines; breadth, 5 inches; sternum, 65 inches; elevation, 2 inches 1 line; length of tail, 2f inches.