. Carnegie Institution of Washington publication. The sculpture of the carapace is best displayed toward the free borders. It consists of abruptly sunken pits, of which there are usually 5 in a line 20 mm. long. Closer to the free borders the pits are smaller. Nowhere does there appear any tendency for the formation of straight rows of pits, such as are seen on the costals of Amyda cariosa, of the New Mexico Wasatch. On the por- tions of the carapace near the midline the pits are less con- spicuous. They appear to be as large, but the walls appear worn down. The hvpoplastron (fig. 650) is thic
. Carnegie Institution of Washington publication. The sculpture of the carapace is best displayed toward the free borders. It consists of abruptly sunken pits, of which there are usually 5 in a line 20 mm. long. Closer to the free borders the pits are smaller. Nowhere does there appear any tendency for the formation of straight rows of pits, such as are seen on the costals of Amyda cariosa, of the New Mexico Wasatch. On the por- tions of the carapace near the midline the pits are less con- spicuous. They appear to be as large, but the walls appear worn down. The hvpoplastron (fig. 650) is thick and heavy. At the .. .... V 1 r suture with the hvoplastron, FIG. 6 r :r not lar from tne midline, the thickness is 13 mm. One border of the notch for the process of the xiphiplastron remains. This bone was articulated with the hypoplastron by a jagged suture and it must have extended anteriorly near the midline. The outer end of the hvpoplastron, near the bases of the lateral processes, is 16 mm. thick. Evidently nearly the whole lower surface of the plastron was covered by the sculptured layer. The pits are smaller than those of the carapace, there being about J pits in a line 20 mm. long. Many of them coalesce to form winding furrows. This species differs from A. fontanus in having a narrower nuchal, much thicker bones, and a considerably coarser sculpture. It is referred to Aspideretes provisionally. Aspideretes vorax sp. nov. Text-fig. 651. This species was collected from the Laramie deposits near Ojo Alamo, San Juan County, New Mexico, in 1904, by Mr. Barnum Brown. The type is in the American Museum of Nat- ural History and has the catalog number 6140. The species is represented, as far as known, by only the nuchal bone; but this is complete. The length of the bone, from side to side, is 200 mm. in a straight line, 215 mm. over the curve. The lateral convexity is considerable and appears to have been somewhat greater than that of either A. austerus or A. fontanus, both
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Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1900, bookyear1908
