. Carnegie Institution of Washington publication. [26 I'OSSI I I IK [ OK NORTH Fl< -Natadochelys ingra- vata. Portion of left xiphi- plastron forming the type. Xi No. 6078 A. II. The fragment of xiphiplastron present indicates a turtle of moderate size, but furnisht with a very thick and heavy plastron. It is estimated that the plastron had a total length of 18 inches (about 460 mm.). The thickness, to the summit of the ischial articular surface, is 26 mm.; at the base of this, where it appears to be rising toward the pubic articular surface, 19 mm.; at the sutural bord
. Carnegie Institution of Washington publication. [26 I'OSSI I I IK [ OK NORTH Fl< -Natadochelys ingra- vata. Portion of left xiphi- plastron forming the type. Xi No. 6078 A. II. The fragment of xiphiplastron present indicates a turtle of moderate size, but furnisht with a very thick and heavy plastron. It is estimated that the plastron had a total length of 18 inches (about 460 mm.). The thickness, to the summit of the ischial articular surface, is 26 mm.; at the base of this, where it appears to be rising toward the pubic articular surface, 19 mm.; at the sutural border for union with the bone of the opposite side, 11 mm. In a specimen of Taphrosphys molops, No. 1474,these measure- ments, in the order given, are 15 mm., 10 mm., and 10 mm. I his specimen is estimated to have had a plastron 21 inches long. The lower surface of the bone is very Hat and smooth. From the outer border the upper surface rises at first rapidly, then more slowly, to the base of the articular eminence, being thus convex. From the hinder border the upper surface rises more and more steeply, being thus concave. The articular surface for the ischium is much larger than in Taphrosphys. It is approximately triangular in outline, the hinder border running somewhat parallel with the hinder border of the bone, while the outer border runs parallel with the outer border (it the bone and about 25 mm. distant from it. This articular surface extends mesiallv to the midline, differing thus from Taphrosphys and resembling Hydromedusa. The figure presented will show the form and extent of the surface. At its summit it has been somewhat eroded, and the border at the anterior angle may have been slightly extended. Where not eroded, the summit is roughened to afford attachment to the ischium. At the anterior angle of the eminence the smooth surface of the plastron at first descends, then begins to ascend,as if rising toward the articular eminence for the pubis; bur no part of this is p
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Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1900, bookyear1908
